Composition, quantum dot-polymer composite, and display device including same

ABSTRACT

A composition including a quantum dot, a dispersing agent for dispersing the quantum dot, a polymerizable monomer including a carbon-carbon double bond, an initiator, a hollow metal oxide particulate, and a solvent, and a quantum dot-polymer composite manufactured from the composition.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2018-0091271 filed in the Korean IntellectualProperty Office on Aug. 6, 2018, and all the benefits accruing therefromunder 35 U.S.C. § 119, the content of which in its entirety is hereinincorporated by reference.

BACKGROUND 1. Field

A composition, a quantum dot-polymer composite manufactured from thesame, and a display device including the same are disclosed.

2. Description of the Related Art

A quantum dot may be applied as a quantum dot-polymer composite to or invarious display devices such as a liquid crystal display, an organiclight emitting diode (OLED), and the like. The quantum dot shouldprovide excellent color reproducibility and high photo-efficiency inorder to be applied to or used in the display devices.

SUMMARY

An embodiment provides a composition for manufacturing a quantumdot-polymer composite.

An embodiment provides a quantum dot-polymer composite.

An embodiment provides a display device including the quantumdot-polymer composite.

An embodiment provides a composition including a quantum dot, adispersing agent for dispersing the quantum dot, a polymerizable monomerincluding a carbon-carbon double bond, an initiator, a hollow metaloxide particulate, and a solvent.

The hollow metal oxide particulate may include a titanium oxide, asilicon oxide, a barium oxide, a zinc oxide, a zirconium oxide, or acombination thereof.

The hollow metal oxide particulate may include TiO₂, SiO₂, BaTiO₃,Ba₂TiO₄, ZnO, ZrO₂, or a combination thereof.

An average particle size of the hollow metal oxide particulate may rangefrom about 200 nanometers (nm) to about 500 nm.

An average particle size of the hollow metal oxide particulate may rangefrom about 250 nm to about 450 nm.

An average size of a hollow portion in the hollow metal oxideparticulate may be greater than or equal to about 10 nm and less thanabout 500 nm.

The average size of a hollow portion in the hollow metal oxideparticulate may be greater than or equal to about 30 nm and less than orequal to about 450 nm.

The quantum dot may include a Group II-VI compound, a Group III-Vcompound, a Group IV-VI compound, a Group IV element or compound, aGroup I-III-VI compound, a Group I-II-IV-VI compound, or a combinationthereof.

The dispersing agent may include a carboxyl group-containing polymer,wherein the carboxyl group-containing polymer may include

a copolymer of a monomer combination including a first monomer includinga carboxyl group and a carbon-carbon double bond, a second monomerincluding a carbon-carbon double bond and a hydrophobic moiety and notincluding a carboxyl group, and optionally a third monomer including acarbon-carbon double bond and a hydrophilic moiety and not including acarboxyl group;

a multiple aromatic ring-containing polymer including a backbonestructure in which two aromatic rings are bound to a quaternary carbonatom that is a constituent atom of another cyclic moiety in the mainchain and including a carboxyl group; or

a combination thereof.

The carboxyl group-containing polymer may have an acid value of greaterthan or equal to about 50 milligrams of potassium hydroxide per gram (mgKOH/g) and less than or equal to about 240 mg KOH/g.

The composition may further include a thiol compound including a thiolgroup at a terminal end of the thiol compound.

The thiol compound may be represented by Chemical Formula 1:

In Chemical Formula 1,

R¹ is hydrogen; a substituted or unsubstituted C1 to C30 linear orbranched alkyl group; a substituted or unsubstituted C6 to C30 arylgroup; a substituted or unsubstituted C3 to C30 heteroaryl group; asubstituted or unsubstituted C3 to C30 cycloalkyl group; a substitutedor unsubstituted C3 to C30 heterocycloalkyl group; a C1 to C10 alkoxygroup; a hydroxy group; —NH₂; a substituted or unsubstituted C1 to C30amine group —NRR′, wherein R and R′ are independently hydrogen or a C1to C30 linear or branched alkyl group and are not simultaneouslyhydrogen; an isocyanate group —R-M=C═O, wherein R is a substituted orunsubstituted C1 to C20 alkylene group and M is an organic or inorganiccation; a halogen; —ROR′, wherein R is a substituted or unsubstituted C1to C20 alkylene group and R′ is hydrogen or a C1 to C20 linear orbranched alkyl group; an acyl halide —RC(═O)X, wherein R is asubstituted or unsubstituted alkylene group and X is a halogen;—C(═O)OR′, wherein R′ is hydrogen or a C1 to C20 linear or branchedalkyl group; —CN; —C(═O)ORR′ or —C(═O)ONRR′, wherein R and R′ areindependently hydrogen or a C1 to C20 linear or branched alkyl group,

L₁ is a carbon atom, a substituted or unsubstituted C1 to C30 alkylenegroup, a substituted or unsubstituted C1 to C30 alkylene group whereinat least one methylene moiety (—CH₂—) is replaced by a sulfonyl moiety(—SO₂—), a carbonyl moiety (CO), —O—, —S—, —SO—, —C(═O)O—, —C(═O)NR—,wherein, R is hydrogen or a C1 to C10 alkyl group, or a combinationthereof, a substituted or unsubstituted C3 to C30 cycloalkylene group, asubstituted or unsubstituted C6 to C30 arylene group, a substituted orunsubstituted C3 to C30 heteroarylene group, or a substituted orunsubstituted C3 to C30 heterocycloalkylene moiety,

Y₁ is a single bond; a substituted or unsubstituted C1 to C30 alkylenegroup; a substituted or unsubstituted C2 to C30 alkenylene group; a C1to C30 alkylene group or a C2 to C30 alkenylene group wherein at leastone methylene moiety (—CH₂—) is replaced by a sulfonyl moiety(—S(═O)₂—), a carbonyl moiety (—C(═O)—), —O—, —S—, —S(═O)—, —C(═O)O—,—C(═O)NR—, wherein R is hydrogen or a C1 to C10 linear or branched alkylgroup, —NR—, wherein R is hydrogen or a C1 to C10 linear or branchedalkyl group, or a combination thereof,

m is an integer of 1 or more,

k1 is 0 or an integer of 1 or more,

k2 is an integer of 1 or more, and

the sum of m and k2 is an integer of 3 or more, provided that m does notexceed the valence of Y₁ and the sum of k1 and k2 does not exceed thevalence of L₁.

An amount of the quantum dot may be greater than or equal to about 10weight percent (wt %) and an amount of the hollow metal oxideparticulate may be greater than or equal to about 5 wt %, based on atotal weight of solids in the composition.

An amount of the hollow metal oxide particulate may be about 5 wt % toabout 80 wt %, based on a total weight of solids in the composition.

An embodiment provides a quantum dot-polymer composite. The quantumdot-polymer composite may be obtained by curing the compositionaccording to an embodiment.

An embodiment provides a display device including a light source and aphotoluminescent element, wherein the photoluminescent element includesthe quantum dot-polymer composite according to an embodiment and thelight source is configured to provide the photoluminescent element withincident light.

The incident light may have a photoluminescence peak wavelength of about440 nm to about 460 nm.

The photoluminescent element may include a sheet including the quantumdot-polymer composite.

The photoluminescent element may be a stack structure including asubstrate and a photoluminescent layer disposed on the substrate,wherein the photoluminescent layer includes a pattern of the quantumdot-polymer composite and the pattern includes at least one repetitivesection configured to emit light at a predetermined wavelength.

The pattern may include a first section configured to emit a first lightand a second section configured to emit a second light having adifferent center wavelength from the first light.

The composition according to an embodiment includes the hollow metaloxide particulate and thereby when light is provided with the quantumdot-polymer composite produced from the composition, the light may bescattered more efficiently. Accordingly, a photo-conversion of thequantum dot-polymer composite may be improved and a display deviceincluding the quantum dot-polymer composite may exhibit high luminance,high efficiency, and high color reproducibility.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages and features of this disclosure willbecome more apparent by describing in further detail exemplaryembodiments thereof with reference to the accompanying drawings, inwhich

FIG. 1 is a schematic view showing that when a film-shaped quantumdot-polymer composite including a scattering body is radiated byincident light, a quantum dot 2 is excited by the incident light andemits light of a specific wavelength, and a scattering body 1 scattersthe incident light, the emitted light by the quantum dot, or acombination thereof,

FIG. 2 is a schematic view showing how a non-hollow particulate-shapedscattering body (left) and a hollow scattering body (right) respectivelycan scatter light,

FIG. 3A is an exploded view showing a display device according to anembodiment,

FIG. 3B is a cross-sectional view showing a display device according toan embodiment,

FIG. 4 is a schematic view showing a process of forming a quantumdot-polymer composite pattern according to an embodiment by using thecomposition according to an embodiment,

FIGS. 5A and 5B are schematic cross-sectional views showing displaydevices according to embodiments, respectively,

FIG. 6 is a cross sectional view showing a display device according toan embodiment,

FIG. 7 is a schematic cross sectional view showing an electroluminescentdevice according to an embodiment,

FIG. 8 is a schematic cross sectional view showing an electroluminescentdevice according to an embodiment,

FIG. 9 is a TEM (Transmission Electronic Microscopy) image showing across section of each film prepared by coating each scatteringbody-dispersion of the Control Synthesis Example, Comparative SynthesisExample 1-1, and Synthesis Example 1-1,

FIG. 10 is a graph of reflectance (wherein SCI is specular componentincluded) of a quantum dot-polymer composite including TiO₂ particulatesas scattering bodies of the Control Example and a quantum dot-polymercomposite including hollow silica as scattering bodies of Example 1-2,

FIG. 11 is a graph of photo-conversion efficiency (CE: ConversionEfficiency (percent (%))) versus weight percent of hollow silica in aquantum dot-polymer composite film including a mixture of TiO₂particulates and hollow silica as scattering bodies, based on totalweight of scattering bodies,

FIG. 12 is a graph of Quantum Efficiency (%) versus weight percent ofhollow silica in the quantum dot-polymer composite film including themixture of TiO₂ particulates and hollow silica as scattering bodies,based on total weight of scattering bodies, and

FIG. 13 is a graph of maintenance percent (%) versus weight percent ofhollow silica in the quantum dot-polymer composite film including themixture of TiO₂ particulates and hollow silica as scattering bodies,based on total weight of scattering bodies.

DETAILED DESCRIPTION

Advantages and characteristics of this disclosure, and a method forachieving the same, will become evident referring to the followingexample embodiments together with the drawings attached hereto. However,the embodiments should not be construed as being limited to theembodiments set forth herein. If not defined otherwise, all terms(including technical and scientific terms) in the specification may bedefined as commonly understood by one skilled in the art. The termsdefined in a generally-used dictionary may not be interpreted ideally orexaggeratedly unless clearly defined. In addition, unless explicitlydescribed to the contrary, the word “comprise” and variations such as“comprises” or “comprising”, will be understood to imply the inclusionof stated elements but not the exclusion of any other elements.

Further, the singular includes the plural unless mentioned otherwise.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. Like reference numerals designate likeelements throughout the specification.

It will be understood that when an element such as a layer, film,region, or substrate is referred to as being “on” another element, itcan be directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” another element, there are no intervening elements present.

It will be understood that, although the terms “first,” “second,”“third” etc. may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, “a first element,” “component,” “region,” “layer,” or“section” discussed below could be termed a second element, component,region, layer, or section without departing from the teachings herein.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother element as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on “upper” sides of the other elements. The exemplary term“lower,” can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below.

“About” as used herein is inclusive of the stated value and means withinan acceptable range of deviation for the particular value as determinedby one of ordinary skill in the art, considering the measurement inquestion and the error associated with measurement of the particularquantity (i.e., the limitations of the measurement system). For example,“about” can mean within one or more standard deviations, or within ±30%,20%, 10%, or 5% of the stated value.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

As used herein, when a definition is not otherwise provided,“substituted” refers to replacement of hydrogen of a compound, a group,or a moiety by a C1 to C30 alkyl group, a C2 to C30 alkynyl group, a C2to C30 epoxy group, a C6 to C30 aryl group, a C7 to C30 alkylaryl group,a C1 to C30 alkoxy group, a C1 to C30 heteroalkyl group, a C3 to C40heteroaryl group, a C3 to C30 heteroalkylaryl group, a C3 to C30cycloalkyl group, a C3 to C15 cycloalkenyl group, a C6 to C30cycloalkynyl group, a C2 to C30 heterocycloalkyl group, a halogen (—F,—Cl, —Br, or —I), a hydroxy group (—OH), a nitro group (—NO₂), athiocyanate group (—SCN), a cyano group (—CN), an amino group (—NRR′wherein R and R′ are independently hydrogen or a C1 to C6 alkyl group),an azido group (—N₃), an amidino group (—C(═NH)NH₂), a hydrazino group(—NHNH₂), a hydrazono group (═N(NH₂), an aldehyde group (—C(═O)H),carbamoyl group (—C(O)NH₂), a thiol group (—SH), an ester group(—C(═O)OR, wherein R is a C1 to C6 alkyl group or a C6 to C12 arylgroup), a carboxyl group (—COOH) or a salt thereof (—C(═O)OM, wherein Mis an organic or inorganic cation), a sulfonic acid group (—SO₃H) or asalt thereof (—SO₃M, wherein M is an organic or inorganic cation), aphosphoric acid group (—PO₃H₂) or a salt thereof (—PO₃MH or —PO₃M₂,wherein M is an organic or inorganic cation), and a combination thereof.

Herein, “functional group” refers to a C1 to C30 alkyl group, a C2 toC30 alkenyl group, a C2 to C30 alkynyl group, a C6 to C30 aryl group, aC7 to C30 alkylaryl group, a C1 to C30 alkoxy group, a C1 to C30heteroalkyl group, a C3 to C30 heteroalkylaryl group, a C3 to C30cycloalkyl group, a C3 to C15 cycloalkenyl group, a C6 to C30cycloalkynyl group, or a C2 to C30 heterocycloalkyl group.

As used herein, when a definition is not otherwise provided, “hetero”refers to inclusion of one or more (e.g., one to three) heteroatoms,wherein the heteroatom(s) may be N, O, S, Si, or P.

As used herein, when a definition is not otherwise provided, “alkylenegroup” refers to a straight or branched saturated aliphatic hydrocarbongroup having at least two valences and optionally substituted with atleast one substituent.

As used herein, when a definition is not otherwise provided, “arylenegroup” refers to a functional group having at least two valencesobtained by removal of at least two hydrogens in at least one aromaticring, and optionally substituted with at least one substituent.

As used herein, when a definition is not otherwise provided, “aliphatic”refers to a C1 to C30 linear or branched hydrocarbon group (e.g., C1 toC30 alkyl, C2 to C30 alkenyl, C2 to C30 alkynyl).

As used herein, when a definition is not otherwise provided, “aromatic”refers to a C6 to C30 aryl group or a C2 to C30 heteroaryl group.

As used herein, when a definition is not otherwise provided, and“alicyclic” refers to a C3 to C30 cycloalkyl group, a C3 to C30cycloalkenyl group, or a C3 to C30 cycloalkynyl group.

As used herein, when a definition is not otherwise provided,“heteroaryl” refers to an aromatic group that comprises at least oneheteroatom covalently bonded to one or more carbon atoms of aromaticring.

As used herein, when a definition is not otherwise provided,“(meth)acrylate” refers to acrylate, methacrylate, or a combinationthereof.

As used herein, when a definition is not otherwise provided,“hydrophobic moiety” refers to a moiety providing the correspondingcompound with a tendency to be agglomerated in an aqueous solution andto repel water.

For example, the hydrophobic moiety may be an aliphatic hydrocarbongroup having a carbon number of 2 or greater (e.g., alkyl, alkenyl,alkynyl, etc.), an aromatic hydrocarbon group having a carbon number of6 or greater (e.g., phenyl, naphthyl, aralkyl group, etc.), or analicyclic hydrocarbon group having a carbon number of 5 or greater(e.g., cyclohexyl, norbornene, norbornane, tricyclodecane, etc.). Thehydrophobic moiety may not be mixed with an ambient medium since thehydrophobic moiety may not be able to form a hydrogen bond with theambient medium, or since the polarity of the hydrophobic moiety may notmatch the polarity of the ambient medium.

As used herein, “visible light” refers to light having a wavelength ofabout 390 nm to about 700 nm.

As used herein, “ultraviolet (UV) ray” refers to a wavelength of greaterthan or equal to about 200 nm and less than about 390 nm.

As used herein, a photo-conversion efficiency (conversion efficiency,CE) refers to a percentage of the photoluminescence amount of the lightdose which the quantum dot-polymer composite absorbs from the excitationlight (e.g., blue light). The total light dose (B) of excitation lightis obtained by integrating the photoluminescence (PL) spectrum of theexcitation light, and the PL spectrum of the quantum dot-polymercomposite is measured, and the light dose (A) of light in a green or redwavelength and the light dose (B′) of light in a blue wavelength areobtained to provide a photo-conversion efficiency (CE) by the followingequation:

A/(B−B′)×100=photo-conversion efficiency (%).

As used herein, “dispersion” refers to a mixture wherein a dispersedphase is a solid and a continuous medium includes a liquid. For example,“dispersion” may refer to a colloidal dispersion wherein the dispersedphase has a dimension of greater than or equal to about 1 nm, forexample, greater than or equal to about 2 nm, greater than or equal toabout 3 nm, or greater than or equal to about 4 nm and severalmicrometers (μm) or less, for example less than or equal to about 2 μm,or less than or equal to about 1 μm.

As used herein, “Group” may refer to a group of Periodic Table.

As used herein, “Group I” may refer to Group IA and Group IB, andexamples may include Li, Na, K, Ru, or Cs but are not limited thereto.

As used herein, “Group II” may refer to Group IIA and Group IIB, andexamples of the Group II metal may be Cd, Zn, Hg, and Mg, but are notlimited thereto.

As used herein, “Group III” may refer to Group IlIA and Group IIIB, andexamples of the Group III metal may be Al, In, Ga, and TI, but are notlimited thereto.

As used herein, “Group IV” may refer to Group IVA and Group IVB, andexamples of a Group IV metal may be Si, Ge, and Sn, but are not limitedthereto. As used herein, “metal” may include a semi-metal such as Si.

As used herein, “Group V” may refer to Group VA, and examples thereofmay include nitrogen, phosphorus, arsenic, antimony, and bismuth, butare not limited thereto.

As used herein, “Group VI” may refer to Group VIA, and examples thereofmay include sulfur, selenium, and tellurium, but are not limitedthereto.

Semiconductor nanocrystal particles also known as quantum dots arecrystalline materials having a size of several nanometers. Suchsemiconductor nanocrystals particles may have a large surface area per aunit volume due to very small sizes and may exhibit differentcharacteristics from bulk materials having the same composition due to aquantum confinement effect. Quantum dots may absorb light from anexcitation source to be excited, and may emit energy corresponding tothe energy bandgap of the quantum dots.

When quantum dots are colloid-synthesized, the particle sizes may berelatively freely controlled and also uniformly controlled. When quantumdots have sizes of less than or equal to about 10 nm, the quantumconfinement effects in which the bandgaps further increase as the sizedecreases may become significant, thus the energy density may beenhanced. As quantum dots have a theoretical quantum efficiency (QY) of100% and may emit light having a high color purity (e.g., full width athalf maximum (FWHM) of less than or equal to about 40 nm), increasedluminous efficiency and improved color reproducibility may be realized.

The quantum dots may be dispersed in a host matrix including a polymer,an inorganic material, or a combination thereof to form a composite inorder to be applied to, e.g., used in, a device. A color filterincluding the quantum dot-polymer composite may provide a device havinghigh luminance, a wide viewing angle, and high color reproducibility.

However, patterning the quantum dot-polymer composite has varioustechnical limits unlike an absorption-type color filter. For example, inorder to obtain the aforementioned effects, the composite may includequantum dots in an increased amount, for example, greater than or equalto about 10%, greater than or equal to about 11%, greater than or equalto about 12%, greater than or equal to about 13%, greater than or equalto about 15%, greater than or equal to about 16%, greater than or equalto about 17%, greater than or equal to about 18%, greater than or equalto about 19%, or greater than or equal to about 20%, based on a totalweight solids, in a sufficiently dispersed state. In addition, foruniform and improved photoluminescence, the composite may include ascattering body in an amount of, for example, greater than or equal toabout 5%, greater than or equal to about 6%, greater than or equal toabout 7%, greater than or equal to about 8%, greater than or equal toabout 9%, or greater than or equal to about 10%, based on a total weightof solids. The scattering body may uniformly spread the light emittedfrom the quantum dots that receive energy in, e.g., of, a certainwavelength to emit light. In addition, the scattering body may not reactwith the host material and may increase an absorption path length ofexcitation light in a host material so that the excitation light maywell be absorbed by the quantum dots.

FIG. 1 is a schematic view showing that when light of a predeterminedwavelength, that is, excitation light is radiated into a film-shapedquantum dot-polymer composite including the scattering body 1, thequantum dots 2 in the composite absorb the excitation light, areexcited, and emit light of a specific wavelength, and the scatteringbody 1 scatters the excitation light, the light of the specificwavelength emitted from the quantum dots 2, or a combination thereof. Inother words, the scattering body 1 in the composite plays a role ofscattering the excitation light, so that the excitation light may bebetter absorbed in the quantum dots 2, and simultaneously, moreuniformly scattering light emitted from the quantum dots 2 in thecomposite.

The increased amounts of the quantum dots and scattering body may reducea dissolubility of the composite for a developing solution in adeveloping process to obtain a pattern. Reducing the dissolubility maymake it difficult to form the quantum dot-polymer composite into adesirable pattern, and particularly, may cause difficulties in themass-production of a pattern, for example filter clogging of a solutionafter the development. In addition, the quantum dots and the scatteringbody may exhibit limited or insufficient dispersibility with respect toa host matrix, particularly, a polymer matrix formed of an organicmaterial, and accordingly, content of the quantum dots, the scatteringbody, or a combination thereof may not be unlimitedly increased.

The present inventors surprisingly found that a composition formanufacturing a quantum dot-polymer composite, which includes hollowmetal oxide particulates as scattering bodies, may include thescattering bodies in a greater quantity due to a lower density than thatof a composition that includes non-hollow metal oxide particulates whenthe scattering bodies have the same average size and are included in thesame weight, e.g., weight percent, and accordingly, may have a higherphoto-conversion efficiency (CE) than the composition including thenon-hollow metal oxide particulates of the same average size in the sameweight, e.g., weight percent.

FIG. 2 is a schematic view showing that a hollow scattering body hasimproved scattering characteristics than a non-hollow particulate-shapedscattering body. As shown at the left of FIG. 2, as the non-hollowparticulate-shaped scattering body has a predetermined refractive index,light radiated into the scattering body is curved and scattered with alittle limited angle and aspect. On the contrary, as shown at the rightof FIG. 2, light radiated into the hollow scattering body is scatteredwith various angles and aspects due to a difference between a refractiveindex of a metal oxide forming the scattering body and an internalrefractive index of the hollow scattering body, and accordingly, thehollow scattering body exhibits improved scattering characteristics.

Accordingly, an embodiment provides a composition for manufacturing aquantum dot-polymer composite including quantum dots, dispersing agentfor dispersing the quantum dots, a polymerizable monomer having acarbon-carbon double bond, an initiator, a solvent, and hollow metaloxide particulates as scattering bodies.

The hollow metal oxide particulates may include a titanium oxide, asilicon oxide, a barium oxide, a zinc oxide, a zirconium oxide, or acombination thereof, but is not limited thereto. The metal oxide may bea mixed metal oxide, for example a mixture of titanium and barium. As anexample, the hollow metal oxide particulates may include TiO₂, SiO₂,BaTiO₃, Ba₂TiO₄, ZnO, ZrO₂, or a combination thereof, and in anembodiment, the hollow metal oxide particulates may be hollow silica(SiO₂), but is not limited thereto.

An average particle size of the hollow metal oxide particulates may beabout 200 nm to about 500 nm, for example, about 210 nm to about 490 nm,about 220 nm to about 480 nm, about 230 nm to about 470 nm, about 240 nmto about 460 nm, about 250 nm to about 450 nm, about 260 nm to about 450nm, about 270 nm to about 450 nm, about 280 nm to about 450 nm, about290 nm to about 450 nm, about 300 nm to about 450 nm, about 300 nm toabout 440 nm, about 300 nm to about 430 nm, about 300 nm to about 420nm, about 300 nm to about 410 nm, or about 300 nm to about 400 nm, butis not limited thereto.

An average size of a hollow portion in the hollow metal oxideparticulates may be greater than or equal to about 10 nm and less thanabout 500 nm. The average size of the hollow may be smaller than thesize of the hollow metal oxide particulate, for example, greater than orequal to about 20 nm and less than or equal to about 490 nm, greaterthan or equal to about 30 nm and less than or equal to about 480 nm,greater than or equal to about 40 nm and less than or equal to about 470nm, greater than or equal to about 50 nm and less than or equal to about460 nm, greater than or equal to about 60 nm and less than or equal toabout 450 nm, greater than or equal to about 70 nm and less than orequal to about 450 nm, greater than or equal to about 80 nm and lessthan or equal to about 450 nm, greater than or equal to about 90 nm andless than or equal to about 450 nm, greater than or equal to about 100nm and less than or equal to about 450 nm, greater than or equal toabout 110 nm and less than or equal to about 450 nm, greater than orequal to about 120 nm and less than or equal to about 450 nm, greaterthan or equal to about 130 nm and less than or equal to about 450 nm,greater than or equal to about 140 nm and less than or equal to about450 nm, greater than or equal to about 150 nm and less than or equal toabout 450 nm, greater than or equal to about 160 nm and less than orequal to about 450 nm, greater than or equal to about 170 nm and lessthan or equal to about 450 nm, greater than or equal to about 180 nm andless than or equal to about 450 nm, greater than or equal to about 190nm and less than or equal to about 450 nm, greater than or equal toabout 200 nm and less than or equal to about 450 nm, greater than orequal to about 210 nm and less than or equal to about 450 nm, greaterthan or equal to about 220 nm and less than or equal to about 450 nm,greater than or equal to about 230 nm and less than or equal to about450 nm, greater than or equal to about 240 nm and less than or equal toabout 450 nm, greater than or equal to about 250 nm and less than orequal to about 450 nm, greater than or equal to about 260 nm and lessthan or equal to about 450 nm, greater than or equal to about 270 nm andless than or equal to about 450 nm, greater than or equal to about 280nm and less than or equal to about 450 nm, greater than or equal toabout 290 nm and less than or equal to about 450 nm, greater than orequal to about 300 nm and less than or equal to about 450 nm, greaterthan or equal to about 300 nm and less than or equal to about 430 nm, orgreater than or equal to about 300 nm and less than or equal to about400 nm, but is not limited thereto.

The hollow metal oxide particulates may be, for example, present in thecomposition in an amount of greater than or equal to about 5 wt %,greater than or equal to about 6 wt %, greater than or equal to about 7wt %, greater than or equal to about 8 wt %, greater than or equal toabout 9 wt %, or greater than or equal to about 10 wt %, based on atotal solid content of the composition. The hollow metal oxideparticulates may be, for example, present in an amount of less than orequal to about 80 wt %, less than or equal to about 75 wt %, less thanor equal to about 70 wt %, less than or equal to about 65 wt %, lessthan or equal to about 60 wt %, less than or equal to about 55 wt %,less than or equal to about 50 wt %, less than or equal to about 45 wt%, less than or equal to about 40 wt %, less than or equal to about 35wt %, less than or equal to about 30 wt %, less than or equal to about25 wt %, or less than or equal to about 20 wt %, based on a total solidcontent of the composition. When the hollow metal oxide particulates arepresent in the composition within the disclosed range, desiredphotoluminescence characteristics of a composite, for example, a desiredrefractive index of a composition or a quantum dot-polymer compositeformed therefrom may be obtained, and in addition, incident light intothe composition or the composite may more likely contact the quantumdots therein.

As described above, the hollow metal oxide particulates in thecomposition for a quantum dot-composite according to an embodiment areinternally hollow and thus a greater number of hollow metal oxideparticulates may be present than the non-hollow metal oxideparticulates, when included at the same weight percent, for example,when the same weight of scattering bodies is present in the same volumeof the quantum dot-composite.

Accordingly, the hollow metal oxide particulates have the same averageparticle diameter as that of the non-hollow metal oxide particulates butmore hollow metal oxide particulates are included and may obtain ahigher scattering effect, and thus, improved photo-conversion efficiencyand maintenance percent compared to the non-hollow metal oxideparticulates.

In the composition, the quantum dots (hereinafter, also referred to assemiconductor nanocrystals) may include a Group II-VI compound, a GroupIII-V compound, a Group IV-VI compound, a Group IV element or compound,a Group I-III-VI compound, a Group I-II-IV-VI compound, or a combinationthereof.

The Group II-VI compound may be a binary element compound such as CdSe,CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, or a combinationthereof; a ternary element compound such as CdSeS, CdSeTe, CdSTe, ZnSeS,ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS,CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, or a combinationthereof; a quaternary element compound such as ZnSeSTe, HgZnTeS,CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS,HgZnSeTe, HgZnSTe, or a combination thereof; or a combination thereof. AGroup II-VI compound that further includes a Group III metal may bereferred to as a Group II-III-VI compound.

The Group III-V compound may be a binary element compound such as GaN,GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, or acombination thereof; a ternary element compound such as GaNP, GaNAs,GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs,InNSb, InPAs, InPSb, or a combination thereof; a quaternary elementcompound such as GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP,GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs,InAlPSb, InZnP, or a combination thereof; or a combination thereof. AGroup III-V compound that further includes a Group II metal (e.g.,InZnP) may be referred to as a Group II-III-V compound.

The Group IV-VI compound may be a binary element compound such as SnS,SnSe, SnTe, PbS, PbSe, PbTe, or a combination thereof; a ternary elementcompound such as SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS,SnPbSe, SnPbTe, or a combination thereof; a quaternary element compoundsuch as SnPbSSe, SnPbSeTe, SnPbSTe, or a combination thereof; or acombination thereof. Examples of the Group I-III-VI compound may includeCuInSe₂, CuInS₂, CuInGaSe, and CuInGaS, but are not limited thereto.

Examples of the Group I-II-IV-VI compound may include CuZnSnSe andCuZnSnS, but are not limited thereto.

The Group IV element or compound may include a single substance such asSi, Ge, or a combination thereof; a binary element compound such as SiC,SiGe, or a combination thereof; or a combination thereof.

The binary element compound, the ternary element compound, or thequaternary element compound may exist in a uniform concentration in aparticle or in different concentrations within the same particle. Thesemiconductor nanocrystal may have a core/shell structure wherein afirst semiconductor nanocrystal surrounds a second semiconductornanocrystal. For example, the core and the shell may have an interfacehaving a concentration gradient wherein the concentration of the elementof the shell decreases toward the core. In addition, the semiconductornanocrystal may have a structure including one semiconductor nanocrystalcore and a multi-layered shell surrounding the core. In an embodiment,the shell may be a multi-layered shell having two or more layers, forexample, 2, 3, 4, 5, or more layers. Each layer of the shell may havethe same composition or different composition from each other. Theadjacent layers may have different compositions from each other. Thematerial of each layer may include a single composition or a combinationof two types of materials (e.g., alloys). At least one element amongmaterials of each layer may have a concentration changing along with aradial direction. For example, at least one layer may have aconcentration gradient of a combination of the two types of materials.For example, at least one layer may include a gradient alloy. The layerincluding the combination of the two types of materials such as alloysmay include a homogeneous composition (e.g., uniform alloy). The layerhaving a concentration gradient of a combination of the two types ofmaterials (e.g., including a gradient alloy) may have a heterogeneousalloy composition and a composition changed in a radial direction.

The quantum dots may include a shell material and a core material havinga different energy bandgap from each other. For example, the energybandgap of the shell material may be larger than that of the corematerial. Alternatively, the energy bandgap of the shell material may beless than that of the core material. When the quantum dot has amulti-layered shell, the energy bandgap of the outer layer may begreater than the energy bandgap of the layer nearer to the core.Alternatively, in the multi-layered shell, the energy bandgap of theouter layer may be less than the energy bandgap of the layer nearer tothe core. The quantum dots may control an absorption/photoluminescencewavelength by adjusting a composition and a size. A maximumphotoluminescence peak wavelength of the quantum dots may be greaterthan or equal to about 460 nm, greater than or equal to about 490 nm,greater than or equal to about 500 nm, greater than or equal to about510 nm, greater than or equal to about 520 nm, greater than or equal toabout 530 nm, greater than or equal to about 540 nm, greater than orequal to about 550 nm, greater than or equal to about 560 nm, greaterthan or equal to about 570 nm, greater than or equal to about 580 nm,greater than or equal to about 590 nm, greater than or equal to about600 nm, greater than or equal to about 610 nm, greater than or equal toabout 620 nm, greater than or equal to about 630 nm, greater than orequal to about 640 nm, greater than or equal to about 650 nm, or greaterthan or equal to about 700 nm. The maximum photoluminescence peakwavelength of the quantum dots may be less than or equal to about 750nm, less than or equal to about 730 nm, less than or equal to about 720nm, less than or equal to about 710 nm, less than or equal to about 700nm, less than or equal to about 690 nm, less than or equal to about 680nm, less than or equal to about 670 nm, less than or equal to about 660nm, less than or equal to about 650 nm, less than or equal to about 640nm, less than or equal to about 630 nm, less than or equal to about 620nm, less than or equal to about 610 nm, less than or equal to about 600nm, less than or equal to about 590 nm, less than or equal to about 580nm, less than or equal to about 570 nm, less than or equal to about 560nm, less than or equal to about 550 nm, less than or equal to about 540nm, less than or equal to about 530 nm, less than or equal to about 520nm, less than or equal to about 510 nm, or less than or equal to about500 nm.

The quantum dots may have quantum efficiency (QE) of greater than orequal to about 10%, for example, greater than or equal to about 20%,greater than or equal to about 30%, greater than or equal to about 50%,greater than or equal to about 60%, greater than or equal to about 70%,greater than or equal to about 90%, or about 100%. The quantum dots mayhave a relatively narrow spectrum so as to improve color purity or colorreproducibility. The quantum dots may have, for example, a full width athalf maximum (FWHM) of a photoluminescence wavelength spectrum of lessthan or equal to about 50 nm, less than or equal to about 45 nm, lessthan or equal to about 40 nm, or less than or equal to about or about 30nm.

The quantum dot may have a particle size, for example, a diameter or thelargest linear length crossing the particle of greater than or equal toabout 1 nm and less than or equal to about 100 nm. The quantum dot mayhave a particle size of about 1 nm to about 50 nm. The quantum dot mayhave a size, for example, greater than or equal to about 2 nm, greaterthan or equal to about 3 nm, or greater than or equal to about 4 nm. Thequantum dot may have a size, for example, less than or equal to about 50nm, less than or equal to about 40 nm, less than or equal to about 30nm, less than or equal to about 20 nm, or less than or equal to about 15nm. The shape of the quantum dots is not particularly limited. Forexample, the shapes of the quantum dots may be a sphere, an oval, apolyhedron, a pyramid, a multipod, a square, a rectangularparallelepiped, a nanotube, a nanorod, a nanowire, a nanosheet, or acombination thereof, but is not limited thereto.

The quantum dots may be commercially available or may be appropriatelysynthesized. When quantum dots are colloid-synthesized, the particlesize may be relatively freely, and also uniformly controlled. Whenquantum dots have a size of less than or equal to about 10 nm, thequantum confinement effects in which the bandgap further increases as asize becomes smaller may become significant, and thus the energy densitymay be enhanced. In a colloid synthesis, precursor materials are reactedin an organic solvent to grow crystal particles, and the organic solventor a ligand compound may coordinate on, e.g., be bound to, the surfaceof the quantum dot, controlling the growth of the particle. Specifictypes of the organic solvent and the ligand compound are known. Excessorganic materials, for example, organic solvent/ligand, etc. that arenot coordinated on, e.g., bound to, the surface of the quantum dotsafter synthesis may be removed by reprecipitation using an excess amountof a non-solvent. Examples of the non-solvent may be acetone, ethanol,methanol, and the like, but are not limited thereto.

The quantum dots may include an organic ligand having a hydrophobicmoiety and not having a photopolymerizable moiety. The organic ligandmoiety may be bound to a surface of the quantum dot. The organic ligandmay include RCOOH, RNH₂, R₂NH, R₃N, RSH, R₃PO, R₃P, ROH, RCOOR′,RPO(OH)₂, R₂POOH (wherein, R and R′ are independently a C1 to C24substituted or unsubstituted aliphatic hydrocarbon group such as a C3 toC24 alkyl or alkenyl group, a C6 to C20 substituted or unsubstitutedaromatic hydrocarbon group such as a C6 to C20 aryl group), or acombination thereof.

Examples of the organic ligand may be a thiol compound such as methanethiol, ethane thiol, propane thiol, butane thiol, pentane thiol, hexanethiol, octane thiol, dodecane thiol, hexadecane thiol, octadecane thiol,or benzyl thiol; an amine compounds such as methane amine, ethane amine,propane amine, butane amine, pentyl amine, hexyl amine, octyl amine,nonyl amine, decyl amine, dodecyl amine, hexadecyl amine, octadecylamine, dimethyl amine, diethyl amine, dipropyl amine, tributylamine, ortrioctylamine; a carboxylic acid compound such as methanoic acid,ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoicacid, heptanoic acid, octanoic acid, dodecanoic acid, hexadecanoic acid,octadecanoic acid, oleic acid, or benzoic acid; a phosphine compoundsuch as methyl phosphine, ethyl phosphine, propyl phosphine, butylphosphine, pentyl phosphine, octyl phosphine, dioctyl phosphine,tributyl phosphine, diphenyl phosphine, triphenyl phosphine, or trioctylphosphine; a phosphine oxide compound such as methyl phosphine oxide,ethyl phosphine oxide, propyl phosphine oxide, butyl phosphine oxidepentyl phosphine oxide, tributyl phosphine oxide, octyl phosphine oxide,dioctyl phosphine oxide, diphenyl phosphine oxide, triphenyl phosphineoxide, or trioctylphosphine oxide; a C5 to C20 alkyl phosphinic acidsuch as hexylphosphinic acid, octylphosphinic acid, dodecanephosphinicacid, tetradecanephosphinic acid, hexadecanephosphinic acid, oroctadecanephosphinic acid; an alkylphosphonic acid such as a C5 to C20alkylphosphonic acid; and the like, but are not limited thereto. Thequantum dots may include a hydrophobic organic ligand that is the same,or a mixture of at least two different hydrophobic organic ligands. Thehydrophobic organic ligand may not include a photopolymerizable moiety,for example, an acrylate group, a methacrylate group, and the like.

An amount of the quantum dots may be greater than or equal to about 10wt %, greater than or equal to about 11 wt %, greater than or equal toabout 12 wt %, greater than or equal to about 13 wt %, greater than orequal to about 14 wt %, greater than or equal to about 15 wt %, greaterthan or equal to about 16 wt %, greater than or equal to about 17 wt %,greater than or equal to about 18 wt %, greater than or equal to about19 wt %, greater than or equal to about 20 wt %, greater than or equalto about 21 wt %, greater than or equal to about 22 wt %, greater thanor equal to about 23 wt %, greater than or equal to about 24 wt %, orgreater than or equal to about 25 wt %, based on a total weight ofsolids in the composition. The amount of the quantum dots may be lessthan or equal to about 70 wt %, less than or equal to about for example,65 wt %, less than or equal to about 60 wt %, less than or equal toabout 55 wt %, less than or equal to about 50 wt %, less than or equalto about 45 wt %, less than or equal to about 40 wt %, less than orequal to about 35 wt %, less than or equal to about 30 wt %, less thanor equal to about 25 wt %, less than or equal to about 20 wt %, lessthan or equal to about 19 wt %, less than or equal to about 17 wt %, orless than or equal to about 15 wt %, based on a total weight of solidsin the composition.

When the quantum dots are simply mixed with a polymer, for example, analkali developable photoresist, or a photocurable thermosetting polymerwithout surface treatment, significant aggregation of the quantum dotsmay occur. In order to apply a patterned quantum dot-polymer compositeto a color filter, a large amount of quantum dots may be included in thecomposite, and patterns may be difficult to form by non-uniformdispersion of the quantum dot. In the composition according to anembodiment, for example, the quantum dots including an organic ligandhaving a hydrophobic moiety on surfaces of the quantum dots may bedispersed in a dispersing agent, for example, a polymer solutionincluding a carboxyl group to obtain quantum dot-polymer dispersion, andthen mixed with a photocurable, or thermally curable other components,for example, a polymerizable (e.g., photopolymerizable or thermallypolymerizable) monomer having a carbon-carbon double bond, an initiator(e.g., photoinitiator or thermal initiator), a hollow metal oxideparticulate, and a solvent, for example, an organic solvent. Thereby, inthe composition according to an embodiment, the quantum dots, forexample, a relatively large amount of the quantum dots may be welldispersed in a photo- or thermally-curable polymer without significantaggregation.

The composition according to an embodiment may be used to provide apattern of a quantum dot-polymer composite. The composition according toan embodiment may be a quantum dot-containing photoresist composition towhich a photolithography method may be applied. The compositionaccording to an embodiment may be an ink composition that may provide apattern by printing, for example, a droplet discharge method, such as,inkjet printing. The composition according to an embodiment may notinclude a conjugated polymer except for a cardo binder resin that willbe described below. The composition according to an embodiment mayinclude a conjugated polymer. Herein, the term “conjugated polymer” mayrefer to a polymer having a conjugated double bond in a main chain ofthe polymer, for example, a polyphenylenevinylene.

In an embodiment, the carboxyl group-containing polymer may be aninsulating polymer. The carboxyl group-containing polymer may include

a copolymer of a monomer mixture including a first monomer including acarboxyl group and a carbon-carbon double bond, and a second monomerincluding a carbon-carbon double bond and a hydrophobic moiety and notincluding a carboxyl group, and optionally a third monomer including acarbon-carbon double bond and a hydrophilic moiety and not including acarboxyl group;

a multiple aromatic ring-containing polymer having a backbone structurein which two aromatic rings are bound to a quaternary carbon atom thatis a constituent atom of another cyclic moiety in the backbone, andincluding a carboxyl group (a cardo binder resin as further describedbelow); or

a combination thereof.

Specific examples of the first monomer may include unsaturatedcarboxylic acid and vinyl carboxylic acid ester compounds such asacrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaricacid, 3-butenoic acid, vinyl acetate, or vinyl benzoate, but are notlimited thereto. One or at least two different first monomers may beused.

Specific examples of the second monomer may be an alkenyl aromaticcompound such as styrene, alpha-methyl styrene, vinyl toluene, or vinylbenzyl methyl ether; an unsaturated carboxylic acid ester compound suchas methyl acrylate, methyl methacrylate, ethyl acrylate, ethylmethacrylate, butyl acrylate, butyl methacrylate, benzyl acrylate,benzyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate,phenyl acrylate, or phenyl methacrylate; an unsaturated carboxylic acidamino alkyl ester compound such as 2-amino ethyl acrylate, 2-amino ethylmethacrylate, 2-dimethyl amino ethyl acrylate, or 2-dimethyl amino ethylmethacrylate; maleimides such as N-phenylmaleimide, N-benzylmaleimide,or N—(C1 to C12 alkyl)maleimide; an unsaturated carboxylic acid glycidylester compound such as glycidyl acrylate, or glycidyl methacrylate; avinyl cyanide compound such as acrylonitrile or methacrylonitrile; anunsaturated amide compound such as acrylamide or methacrylamide, but arenot limited thereto. One or at least two different second monomers maybe used.

Specific examples of the third monomer may include 2-hydroxyethylacrylate, 2-hydroxyethyl methacrylate, 2-hydroxybutyl acrylate, or2-hydroxybutyl methacrylate, but are not limited thereto. One or atleast two different third monomers may be used.

When the carboxyl group-containing polymer is a copolymer of a mixtureincluding the first monomer, the second monomer, and optionally thethird monomer, in the copolymer an amount of a first repeating unitderived from the first monomer may be greater than or equal to about 10mole percent (mol %), for example, greater than or equal to about 15 mol%, greater than or equal to about 25 mol %, or greater than or equal toabout 35 mol %, and the amount of the first repeating unit may be lessthan or equal to about 90 mol %, for example, less than or equal toabout 89 mol %, less than or equal to about 80 mol %, less than or equalto about 70 mol %, less than or equal to about 60 mol %, less than orequal to about 50 mol %, less than or equal to about 40 mol %, less thanor equal to about 35 mol %, or less than or equal to about 25 mol %.

In the carboxyl group-containing polymer, an amount of a secondrepeating unit derived from the second monomer may be greater than orequal to about 10 mol %, for example, greater than or equal to about 15mol %, greater than or equal to about 25 mol %, or greater than or equalto about 35 mol % and the amount of the second repeating unit may beless than or equal to about 90 mol %, for example, less than or equal toabout 89 mol %, less than or equal to about 80 mol %, less than or equalto about 70 mol %, less than or equal to about 60 mol %, less than orequal to about 50 mol %, less than or equal to about 40 mol %, less thanor equal to about 35 mol %, or less than or equal to about 25 mol %, ifpresent.

In the carboxyl group-containing polymer, an amount of a third repeatingunit derived from the third monomer, if present, may be greater than orequal to about 1 mol %, for example, greater than or equal to about 5mol %, greater than or equal to about 10 mol %, or greater than or equalto about 15 mol % and the amount of the third repeating unit may be lessthan or equal to about 30 mol %, less than or equal to about forexample, 25 mol %, less than or equal to about 20 mol %, less than orequal to about 18 mol %, less than or equal to about 15 mol %, or lessthan or equal to about 10 mol %.

The carboxyl group-containing polymer may be a copolymer of(meth)acrylic acid; and at least one second/third monomer that is anaryl or alkyl (meth)acrylate, a hydroxyalkyl (meth)acrylate, or styrene.For example, the carboxyl group-containing polymer may be a methacrylicacid/methyl methacrylate copolymer, a methacrylic acid/benzylmethacrylate copolymer, a methacrylic acid/benzyl methacrylate/styrenecopolymer, a methacrylic acid/benzyl methacrylate/2-hydroxyethylmethacrylate copolymer, or a methacrylic acid/benzylmethacrylate/styrene/2-hydroxyethyl methacrylate copolymer.

The carboxyl group-containing polymer may include a multiple aromaticring-containing polymer, in particular a multiple aromaticring-containing polymer including a backbone structure in which twoaromatic rings are bound to a quaternary carbon atom that is aconstituent atom of another cyclic moiety in the main chain andincluding a carboxyl group. The multiple aromatic ring-containingpolymer is known as a “cardo binder resin” and may commerciallyavailable. A variety of cardo binder resins are described, for example,in U.S. Pat. No. 8,530,537, which is incorporated herein by reference inits entirety.

The carboxyl group-containing polymer may have an acid value of greaterthan or equal to about 50 mg KOH/g. For example, the carboxylgroup-containing polymer may have an acid value of greater than or equalto about 60 mg KOH/g, greater than or equal to about 70 mg KOH/g,greater than or equal to about 80 mg KOH/g, greater than or equal toabout 90 mg KOH/g, greater than or equal to about 100 mg KOH/g, greaterthan or equal to about 110 mg KOH/g, greater than or equal to about 120mg KOH/g, greater than or equal to about 125 mg KOH/g, or greater thanor equal to about 130 mg KOH/g. The acid value of the carboxylgroup-containing polymer may be for example, less than or equal to about250 mg KOH/g, for example, less than or equal to about 240 mg KOH/g,less than or equal to about 230 mg KOH/g, less than or equal to about220 mg KOH/g, less than or equal to about 210 mg KOH/g, less than orequal to about 200 mg KOH/g, less than or equal to about 190 mg KOH/g,less than or equal to about 180 mg KOH/g, or less than or equal to about160 mg KOH/g, but is not limited thereto.

The carboxyl group-containing polymer may have a weight averagemolecular weight of greater than or equal to about 1,000 grams per mole(g/mol), for example, greater than or equal to about 2,000 g/mol,greater than or equal to about 3,000 g/mol, or greater than or equal toabout 5,000 g/mol. The carboxyl group-containing polymer may have aweight average molecular weight of less than or equal to about 100,000g/mol, or less than or equal to about 50,000 g/mol.

In the composition, an amount of the carboxyl group-containing polymermay be greater than or equal to about 0.5 wt %, for example, greaterthan or equal to about 1 wt %, greater than or equal to about 5 wt %,greater than or equal to about 10 wt %, greater than or equal to about15 wt %, or greater than or equal to about 20 wt %, based on a totalweight of the composition, but is not limited thereto. The amount of thecarboxyl group-containing polymer may be less than or equal to about 35wt %, for example less than or equal to about 33 wt %, less than orequal to about 30 wt %, based on a total weight of the composition.Within the ranges, the carboxyl group-containing polymer may ensuredispersibility of the quantum dot. In an embodiment, the amount of thecarboxyl group-containing polymer may be about 0.5 wt % to about 55 wt%, based on a total weight of solids in the composition.

In the composition, the polymerizable (e.g., photopolymerizable) monomerincluding the carbon-carbon double bond may include an (e.g.,photopolymerizable) (meth)acryl-based monomer. The monomer may be aprecursor for an electronically insulating polymer. The acryl-basedmonomer may include a (C1 to C18 alkyl) (meth)acrylate such as ethyleneglycol di(meth)acrylate, triethylene glycol di(meth)acrylate, diethyleneglycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanedioldi(meth)acrylate, neopentylglycol di(meth)acrylate, pentaerythritoldi(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritoltetra (meth)acrylate, dipentaerythritol di(meth)acrylate,dipentaerythritol tri(meth)acrylate, dipentaerythritolpenta(meth)acrylate, pentaerythritol hexa(meth)acrylate, bisphenol Adi(meth)acrylate, bisphenol A epoxy acrylate, trimethylolpropanetri(meth)acrylate, ethylene glycol monomethyl ether (meth)acrylate,novolac epoxy (meth)acrylate, diethylene glycol di(meth)acrylate,triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate,tris(meth)acryloyloxyethyl phosphate, or a combination thereof.

An amount of the monomer may be greater than or equal to about 0.5 wt %,for example, greater than or equal to about 1 wt %, or greater than orequal to about 2 wt %, based on a total weight of the composition. Theamount of the photopolymerizable monomer may be less than or equal toabout 30 wt %, for example, less than or equal to about 28 wt %, lessthan or equal to about 25 wt %, less than or equal to about 23 wt %,less than or equal to about 20 wt %, less than or equal to about 18 wt%, less than or equal to about 17 wt %, less than or equal to about 16wt %, or less than or equal to about 15 wt %, based on a total weight ofthe composition.

The initiator in the composition may be used for polymerization of theaforementioned monomers. The initiator is a compound accelerating aradical reaction (e.g., radical polymerization of monomer) by producingradical chemical species under a mild condition (e.g., by heat orlight). The initiator may be a thermal initiator or a photoinitiator.Examples of the thermal initiator may be azobisisobutyronitrile, benzoylperoxide, and the like, but are not limited thereto. The photoinitiatoris a compound capable of initiating a radical polymerization of theaforementioned photo-polymerizable acrylic monomer, a thiol compound(which will be described later), or a combination thereof by light. Thetype of the photoinitiator is not particularly limited. Thephotoinitiator may include a triazine-based compound, an acetophenonecompound, a benzophenone compound, a thioxanthone compound, a benzoincompound, an oxime ester compound, an aminoketone compound, a phosphineor phosphine oxide compound, a carbazole-based compound, a diketonecompound, a sulfonium borate-based compound, a diazo-based compound, abiimidazole-based compound, or a combination thereof, but is not limitedthereto. Each of the aforementioned initiators is known, but is notparticularly limited.

In the composition, an amount of the initiator may be appropriatelyadjusted considering types and amounts of the used photopolymerizablemonomer. In an embodiment, an amount of the initiator may be about 0.01wt % to about 10 wt %, based on a total weight of the composition, butis not limited thereto.

The composition may further include a (multiple or mono-functional)thiol compound having at least one thiol group at a terminal end of the(multiple or mono-functional) thiol compound.

The thiol compound may be a dithiol compound, a trithiol compound, atetrathiol compound, or a combination thereof. For example, the thiolcompound may be glycol di-3-mercaptopropionate, glycol dimercaptoacetate(e.g., ethylene glycol dimercaptoacetate), trimethylolpropanetris(3-mercaptopropionate), pentaerythritoltetrakis(3-mercaptopropionate), pentaerythritoltetrakis(2-mercaptoacetate), 1,6-hexanedithiol, 1,3-propanedithiol,1,2-ethanedithiol, a polyethylene glycol dithiol including 1 to 10ethylene glycol repeating units, or a combination thereof.

In an embodiment, the thiol compound may be represented by ChemicalFormula 1:

In Chemical Formula 1,

R¹ is hydrogen; a substituted or unsubstituted C1 to C30 linear orbranched alkyl group; a substituted or unsubstituted C6 to C30 arylgroup; a substituted or unsubstituted C3 to C30 heteroaryl group; asubstituted or unsubstituted C3 to C30 cycloalkyl group; a substitutedor unsubstituted C3 to C30 heterocycloalkyl group; a C1 to C10 alkoxygroup; a hydroxy group; —NH₂; a substituted or unsubstituted C1 to C30amine group (—NRR′, wherein R and R′ are independently hydrogen or a C1to C30 linear or branched alkyl group and are not simultaneouslyhydrogen); an isocyanate group (—R-M=C═O, wherein R is a substituted orunsubstituted C1 to C20 alkylene group and M is an organic or inorganiccation); a halogen; —ROR′ (wherein R is a substituted or unsubstitutedC1 to C20 alkylene group and R′ is hydrogen or a C1 to C20 linear orbranched alkyl group); an acyl halide (—RC(═O)X, wherein R is asubstituted or unsubstituted alkylene group and X is a halogen);—C(═O)OR′ (wherein R′ is hydrogen or a C1 to C20 linear or branchedalkyl group); —CN; —C(═O)ORR′ or —C(═O)ONRR′ (wherein R and R′ areindependently hydrogen or a C1 to C20 linear or branched alkyl group),

L₁ is a carbon atom, a substituted or unsubstituted C1 to C30 alkylenegroup, a substituted or unsubstituted C1 to C30 alkylene group whereinat least one methylene moiety (—CH₂—) is replaced by a sulfonyl moiety(—SO₂—), a carbonyl moiety (CO), —O—, —S—, —SO—, —C(═O)O—, —C(═O)NR—(wherein R is hydrogen or a C1 to C10 alkyl group), or a combinationthereof, a substituted or unsubstituted C3 to C30 cycloalkylene group, asubstituted or unsubstituted C6 to C30 arylene group, a substituted orunsubstituted C3 to C30 heteroarylene group, or a substituted orunsubstituted C3 to C30 heterocycloalkylene moiety,

Y₁ is a single bond; a substituted or unsubstituted C1 to C30 alkylenegroup; a substituted or unsubstituted C2 to C30 alkenylene group; or aC1 to C30 alkylene group or a C2 to C30 alkenylene group wherein atleast one methylene moiety (—CH₂—) is replaced by a sulfonyl moiety(—S(═O)₂—), a carbonyl moiety (—C(═O)—), —O—, —S—, —S(═O)—, —C(═O)O—,—C(═O)NR— (wherein R is hydrogen or a C1 to C10 linear or branched alkylgroup), —NR— (wherein R is hydrogen or a C1 to C10 linear or branchedalkyl group), or a combination thereof,

m is an integer of 1 or more,

k1 is 0 or an integer of 1 or more,

k2 is an integer of 1 or more, and

the sum of m and k2 is an integer of 3 or more, provided that m does notexceed the valence of Y₁ and the sum of k1 and k2 does not exceed thevalence of L₁.

An amount of the thiol compound may be less than or equal to about 10 wt%, for example, less than or equal to about 9 wt %, less than or equalto about 8 wt %, less than or equal to about 7 wt %, less than or equalto about 6 wt %, or less than or equal to about 5 wt %, based on a totalweight of the composition. The amount of the thiol compound may begreater than or equal to about 0.1 wt %, for example, greater than orequal to about 0.5 wt % or greater than or equal to about 1 wt %, basedon a total weight of the composition.

The solvent may be an organic solvent (or a liquid vehicle) and types ofusable organic solvents are not particularly limited. Types and amountsof the organic solvent may be appropriately determined by consideringthe aforementioned main components, that is the quantum dot, thedispersing agent, polymerizable monomer, the initiator, the scatteringbody that is the hollow metal particulate oxide, the thiol compound ifused, and types and amounts of an additive which is described later. Thecomposition may include a solvent in a residual amount except for adesired amount of the (non-volatile) solid. Examples of the solvent (orliquid vehicle) may include ethylene glycols such as ethyl 3-ethoxypropionate, ethylene glycol, diethylene glycol, or polyethylene glycol;glycol ethers such as ethylene glycol monomethyl ether, ethylene glycolmonoethyl ether, diethylene glycol monomethyl ether, ethylene glycoldiethyl ether, or diethylene glycol dimethyl ether; glycol etheracetates such as ethylene glycol acetate, ethylene glycol monoethylether acetate, diethylene glycol monoethyl ether acetate, or diethyleneglycol monobutyl ether acetate; propylene glycols such as propyleneglycol; propylene glycol ethers such as propylene glycol monomethylether, propylene glycol monoethyl ether, propylene glycol monopropylether, propylene monobutyl ether, propylene glycol dimethylether,dipropylene glycol dimethyl ether, propylene glycol diethyl ether, ordipropylene glycol diethyl ether; propylene glycol ether acetates suchas propylene glycol monomethyl ether acetate, or dipropylene glycolmonoethyl ether acetate; amides such as N-methylpyrrolidone, dimethylformamide, or dimethyl acetamide; ketones such as methylethylketone(MEK), methylisobutylketone (MIBK), or cyclohexanone; petroleums such astoluene, xylene, or solvent naphtha; esters such as ethyl acetate, butylacetate, or ethyl lactate; ethers such as diethyl ether, dipropyl ether,or dibutyl ether; aliphatic, alicyclic, or aromatic hydrocarbons; orcarboxylate/ester derivatives (e.g., cyclohexyl acetates), and mixturesthereof.

If desired, the composition may further include various additives, suchas a leveling agent, a coupling agent, or a combination thereof inaddition to the aforementioned components. The amount of the additive isnot particularly limited, and may be controlled within an appropriaterange wherein the additive does not cause an adverse effect onpreparation of the composition and production of the quantum dot-polymercomposite and optionally a patterning of the composite. Theaforementioned additives may be known compounds or materials havingdesirable functions and are not particularly limited.

If used, an amount of the additives may be greater than or equal toabout 0.1 wt %, for example, greater than or equal to about 0.5 wt %,greater than or equal to about 1 wt %, greater than or equal to about 2wt %, or greater than or equal to about 5 wt %, based on a total weightof the composition, but is not limited thereto. If used, the amount ofthe additives may be less than or equal to about 20 wt %, for exampleless than or equal to about 19 wt %, less than or equal to about 18 wt%, less than or equal to about 17 wt %, less than or equal to about 16wt %, or less than or equal to about 15 wt %, based on a total weight ofthe composition, but is not limited thereto.

The composition may be manufactured by mixing the above componentsappropriately. In an embodiment, the quantum dots and the scatteringbody (as inorganic materials) may not be well-dispersed in the solvent(as an organic material), and thus, in order to obtain uniformdispersion, each of or both of the quantum dots and the scattering bodymay be predispersed in the dispersing agent for dispersing the quantumdots, and then may be mixed in the solvent.

An embodiment provides a quantum dot-polymer composite obtained bycuring the composition according to an embodiment.

The quantum dot-polymer composite includes a polymer matrix and quantumdots dispersed in the polymer matrix, and the aforementioned hollowmetal particulate oxide.

The polymer matrix may include the aforementioned dispersing agent and apolymerization product of the aforementioned polymerizable monomerhaving the carbon-carbon double bond by the aforementioned initiator(thermal initiator or photoinitiator) in the composition according to anembodiment. In an embodiment, when the composition according to anembodiment further includes the aforementioned thiol compound having atleast one thiol group at a terminal end of the thiol compound, thepolymer matrix may further include a thiolene resin. The polymer matrixmay include the dispersing agent, the polymerization product of thepolymerizable monomer having the carbon-carbon double bond, across-linked polymer formed by cross-linking the thiolene resin, or acombination thereof. In an embodiment, the thiol compound having atleast one thiol group at a terminal end of the thiol compound may be amultiple thiol compound having at least two thiol groups at a terminalend of the thiol compound, and in this case, the polymer matrix mayinclude a polymerization product between the multiple thiol compounds.The polymer matrix may not include a conjugated polymer (except for acardo binder resin).

The quantum dot-polymer composite may be in the form of a film. The filmmay have for example a thickness of less than or equal to about 30 μm,for example, less than or equal to about 10 μm, less than or equal toabout 8 μm, or less than or equal to about 7 μm and greater than about 2μm, for example, greater than or equal to about 3 μm, greater than orequal to about 3.5 μm, or greater than or equal to about 4 μm. Thequantum dot-polymer composite includes the hollow metal oxideparticulates as scattering bodies and thus may include more scatteringbodies than a quantum dot-polymer composite including non-hollow metaloxide particulates, and thereby may exhibit an improved photo-conversionefficiency and maintenance percent.

An embodiment provides a display device including a light source and aphotoluminescent element, wherein the photoluminescent element includesthe quantum dot-polymer composite according to an embodiment, and thelight source is configured to provide the photoluminescent element withincident light.

The incident light may have a photoluminescence peak wavelength ofgreater than or equal to about 440 nm, for example, greater than orequal to about 450 nm and less than or equal to about 460 nm.

The photoluminescent element may include a sheet including, e.g., of,the quantum dot-polymer composite. In an embodiment, the display devicemay further include a liquid crystal panel. The sheet including, e.g.,of the quantum dot-polymer composite may be disposed between the lightsource and the liquid crystal panel. FIG. 3 is an exploded view of anon-limiting display device.

Referring to FIG. 3A, the display device may have a structure wherein areflector, a light guide panel (LGP) and a blue LED light source(Blue-LED), the aforementioned quantum dot (QD)-polymer composite sheet(QD sheet), and, for example, various optical films, such as, a prism, adouble brightness enhance film (DBEF), and the like, are stacked and aliquid crystal panel is disposed thereon.

The display device may not include a liquid crystal layer. The displaydevice may include a blue organic light emitting diode (OLED) as a lightsource. Referring to FIG. 3B, the display device may include a (blue)organic light emitting diode (OLED) as a light source and a quantumdot-polymer composite sheet including a mixture of red and green quantumdots thereon. On the quantum dot-polymer composite sheet, anabsorption-type color filter layer (having R/G/B sections) and asubstrate may be disposed.

The organic light emitting diode (OLED) may include at least two pixelelectrodes formed on the substrate, a pixel define layer formed betweenthe adjacent pixel electrodes, and an organic emission layer formed oneach pixel electrode, and a common electrode layer formed on the organicemission layer.

The substrate may include an insulating material and may haveflexibility. Details for the substrate are described hereinafter.

A line layer including a thin film transistor or the like is formed onthe substrate. The line layer may further include a gate line, a sustainvoltage line, a gate insulating layer, a data line, a source electrode,a drain electrode, a semiconductor, a protective layer, and the like.The detail structure of the line layer may be verified according to anembodiment. The gate line and the sustain voltage line are electricallyseparated from each other, and the data line is insulated and crossingthe gate line and the sustain voltage line. The gate electrode, thesource electrode, and the drain electrode form a control terminal, aninput terminal, and an output terminal of the thin film transistor,respectively. The drain electrode is electrically connected to the pixelelectrode that will be described later.

The pixel electrode may function as an anode of the display device. Thepixel electrode may be formed of a transparent conductive material suchas indium tin oxide (ITO) or indium zinc oxide (IZO). The pixelelectrode may be formed of a material having a light-blocking propertiessuch as gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium(Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium(Pd), or titanium (Ti). The pixel electrode may have a two-layeredstructure in which the aforementioned transparent conductive materialand the aforementioned material having light-blocking properties arestacked sequentially.

Between two adjacent pixel electrodes, a pixel define layer (PDL)overlapped with a terminal end of the pixel electrode to divide thepixel electrode into a pixel unit. The pixel define layer is aninsulation layer which may electrically block the at least two pixelelectrodes.

The pixel define layer covers a portion of the upper surface of thepixel electrode, and the remaining region of the pixel electrode notcovered by the pixel define layer may provide an opening. An organicemission layer that will be described later may be formed on the regiondefined by the opening.

The organic emission layer defines each pixel area by the aforementionedpixel electrode and pixel define layer. In other words, one pixel areamay be defined as an area where is formed with one organic emission unitlayer which is contacted with one pixel electrode divided by the pixeldefine layer.

For example, in the display device according to an embodiment, theorganic emission layer may be defined as a first pixel area, a secondpixel area and a third pixel area, and each pixel area is spaced apartfrom each other leaving a predetermined interval by the pixel definelayer.

In an embodiment, the organic emission layer may emit a third lightbelonging to a visible light region or to a UV region. That is, each ofthe first to the third pixel areas of the organic emission layer mayemit a third light. In an embodiment, the third light may be a lighthaving the highest energy in the visible light region, for example, maybe blue light. When all pixel areas of the organic emission layer aredesigned to emit the same light, e.g., light of the same color, eachpixel area of the organic emission layer may be all formed of the sameor similar materials or may exhibit the same or similar properties.Accordingly, a process difficulty of forming the organic emission layermay be relieved, and the display device may be applied for, e.g., usedin, a large scale/large area process. However, the organic emissionlayer according to an embodiment is not necessarily limited thereto, butthe organic emission layer may be designed to emit at least twodifferent lights, e.g., at least two different colored lights.

The organic emission layer includes an organic emission unit layer ineach pixel area, and each organic emission unit layer may furtherinclude an auxiliary layer (e.g., hole injection layer (HIL), holetransport layer (HTL), electron transport layer (ETL), etc.) besides theemission layer.

The common electrode may function as a cathode of the display device.The common electrode may be formed of a transparent conductive materialsuch as indium tin oxide (ITO) or indium zinc oxide (IZO). The commonelectrode may be formed on the organic emission layer and may beintegrated therewith.

A planarization layer or a passivation layer may be formed on the commonelectrode. The planarization layer may include a (e.g., transparent)insulating material for ensuring electrical insulation with the commonelectrode.

The absorption-type color filter layer may be formed corresponding toeach pixel area. The absorption-type color filter layer may include a Gsection configured to selectively transmit green light and to absorb andblock light in the other wavelength region, a R section configured toselectively transmit red light and to absorb and block light in theother wavelength region, and a B section configured to selectivelytransmit blue light and to absorb green light and red light.

In an embodiment, the display device may include a light source and aphotoluminescent element including a photoluminescent layer, wherein thelight source is configured to provide the photoluminescent layer withlight and the photoluminescent layer may include a pattern of theaforementioned quantum dot-polymer composite.

The photoluminescent layer may be included in the display device as astack structure disposed on the substrate.

The photoluminescent layer may include a pattern of the quantumdot-polymer composite and the pattern may include at least one repeatingsection emitting light in a predetermined wavelength.

In an embodiment, the pattern of the quantum dot-polymer composite mayinclude a first section configured to emit a first light, a secondsection configured to emit a second light, or a combination thereof.

The first light and the second light may have different maximumphotoluminescence wavelengths in photoluminescence spectra. In anembodiment, the first light may be red light having a maximumphotoluminescence wavelength of about 600 nm to about 650 nm (e.g.,about 620 nm to about 650 nm) and the second light may be green lighthaving a maximum photoluminescence wavelength of about 500 nm to about550 nm (e.g., about 510 nm to about 550 nm). The pattern of the quantumdot-polymer composite may further include a third section configured toemit or transmit a third light (e.g., blue light) that is different fromthe first light and the second light. A maximum peak wavelength of thethird light may be greater than or equal to about 380 nm, for example,greater than or equal to about 420 nm, greater than or equal to about430 nm, greater than or equal to about 440 nm, or greater than or equalto about 445 nm and less than or equal to about 480 nm, for example,less than or equal to about 470 nm, less than or equal to about 460 nm,or less than or equal to about 455 nm. The light source may emit thethird light.

In the patterned film of the quantum dot-polymer composite in a displaydevice according to an embodiment, the first section may be a red lightemitting section, the second section may be a green light emittingsection, and the light source may be an element emitting blue light. Inthis case, an optical element to block (e.g., reflects or absorbs) bluelight may be disposed on the front surface (light emitting surface) ofthe first section and the second section

The substrate may be a substrate including an insulating material. Thesubstrate may include glass; various polymers such as polyesters (e.g.,polyethylene terephthalate (PET) or polyethylene naphthalate (PEN)),polycarbonate, polyacrylate, and the like; inorganic materials such aspolysiloxane (e.g., polydimethylsiloxane (PDMS)); Al₂O₃, ZnO, and thelike; or a combination thereof, but is not limited thereto. A thicknessof the substrate may be appropriately selected considering a substratematerial, but is not particularly limited. The substrate may haveflexibility. The substrate may be configured to have a transmittance ofgreater than or equal to about 50%, greater than or equal to about 60%,greater than or equal to about 70%, greater than or equal to about 80%,or greater than or equal to about 90% for light emitted from the quantumdot.

In an embodiment, the aforementioned stack structure may be manufacturedusing a photoresist (PR) composition. Such a method may include

forming a film of the aforementioned composition on a substrate;

exposing a selected region of the film to light (e.g., a wavelength ofless than or equal to about 400 nm); and developing the exposed filmwith an alkali developing solution to obtain a pattern of the quantumdot-polymer composite.

The substrate and the composition have the same specification asdescribed above. Non-limiting methods of forming the pattern areillustrated, referring to FIG. 4.

The aforementioned composition is coated to have a predeterminedthickness on a substrate in an appropriate method of spin coating, slitcoating, and the like. The formed film may be, optionally, pre-baked(PRB). The pre-baking may be performed by selecting an appropriatecondition from conditions of a temperature, time, an atmosphere, and thelike.

The formed (or optionally pre-baked) film is exposed (EXP) to lighthaving a predetermined wavelength under a mask having a predeterminedpattern. A wavelength and intensity of the light may be selectedconsidering types and amounts of the photoinitiator, types and amountsof the quantum dots, and the like.

The exposed film is treated with an alkali developing solution (e.g., bydipping or spraying) to dissolve an unexposed region and obtain adesired pattern. The obtained pattern may be, optionally, post-baked(POB) to improve crack resistance and solvent resistance of the pattern,for example, at about 150° C. to about 230° C. for a predetermined time(e.g., greater than or equal to about 10 minutes or greater than orequal to about 20 minutes).

When the quantum dot-polymer composite pattern has a plurality ofrepetitive sections, a quantum dot-polymer composite having a desiredpattern may be obtained by preparing a plurality of compositionsincluding quantum dots having desired photoluminescence properties (aphotoluminescence peak wavelength and the like) to form each repetitivesection (e.g., a red light emitting quantum dot, a green quantum dot, oroptionally, a blue quantum dot) and repeating the aforementionedformation processes of the pattern regarding each composition a numberof times (e.g., twice or more or three times or more).

For example, the quantum dot-polymer composite may have a pattern of atleast two repetitive color sections (e.g., RGB sections). This quantumdot-polymer composite pattern may be used as a photoluminescence-typecolor filter (C/F) in a display device.

In an embodiment, the aforementioned stack structure may be manufacturedusing an ink composition. Such a method may include depositing the inkcomposition on a desired substrate or an organic light emitting diodethat will be described later (e.g., blue light emitting OLED) (e.g., soas to have a desired pattern) by using an appropriate system (e.g., adroplet discharging apparatus, such as an inkjet or a nozzle printingdevice), and performing removal of a solvent by heating the same andpolymerization. By such a method, a highly precise quantum dot-polymercomposite film or pattern may be formed in a simple manner within ashort time.

In a display device according to an embodiment, the light source mayinclude, for example, an organic light emitting diode (OLED).

FIGS. 5A and 5B are schematic cross-sectional views of display devicesaccording to embodiments. Referring to FIG. 5A and FIG. 5B, a lightsource may include an organic light emitting diode (OLED) (e.g.,emitting blue light or light in a wavelength of less than or equal toabout 500 nm). The organic light emitting diode (OLED) is the same asdescribed above. Pixel areas of the organic light emitting diode (OLED)may be disposed corresponding to the first, second, and third sections.

On the light source, disposed is a stack structure including the patternof the quantum dot-polymer composite (e.g., including a first sectionincluding red quantum dots and a second section including green quantumdots) and a substrate (e.g., directly on the light source). The (e.g.,blue) light emitted from a light source enters the first section and thesecond section configured to emit red and green light, respectively. Theblue light emitted from a light source may transmit the third section.An optical element (blue light blocking layer or first optical filter)blocking (e.g., reflecting or absorbing) blue light may be disposed onthe first section emitting red light and the second section emittinggreen light

The blue light blocking layer may be disposed on the substrate. The bluelight blocking layer may be disposed on the first section and the secondsection between the substrate and the quantum dot-polymer compositepattern. A detailed description of the blue light blocking layer is thesame as that of a first optical filter which will be described later.

Such a device may be manufactured by separately manufacturing theaforementioned stack structure and (e.g., blue light-emitting) OLED, andthen, assembling them. The device may be manufactured by directlyforming a quantum dot-polymer composite pattern on the OLED.

In an embodiment, the display device may further include a lowersubstrate, a polarizer disposed under the lower substrate, and a liquidcrystal layer disposed between the stack structure and the lowersubstrate, wherein the stack structure is disposed so that thephotoluminescent layer (hereinafter, also referred to as a quantumdot-polymer composite pattern) faces the liquid crystal layer. Thedisplay device may further include a polarizer between the liquidcrystal layer and the photoluminescent layer. The light source mayfurther include LED, and if desired, a light guide panel.

Non-limiting examples of the display device (e.g., a liquid crystaldisplay device) according to an embodiment are illustrated with areference to a drawing. FIG. 6 is a schematic cross sectional viewshowing a liquid crystal display (LCD) according to an embodiment.Referring to FIG. 6, the display device of an embodiment includes aliquid crystal panel 200, a polarizer 300 disposed under the liquidcrystal panel 200, and a backlight unit (BLU) disposed under thepolarizer 300.

The liquid crystal panel 200 includes a lower substrate 210, a stackstructure, and a liquid crystal layer 220 disposed between the stackstructure and the lower substrate. The stack structure includes a (e.g.,transparent and insulating) substrate 240 and a photoluminescent layer230 including a quantum dot-polymer composite pattern.

The lower substrate 210 which is also referred to be an array substratemay be a transparent insulating material substrate. The substrate is thesame as described above. A line plate 211 is provided on an uppersurface of the lower substrate 210. The line plate 211 may include aplurality of gate lines (not shown) and data lines (not shown) thatdefine a pixel area, a thin film transistor disposed adjacent to acrossing region of the gate lines and data lines, and a pixel electrodefor each pixel area, but is not limited thereto. Details of such lineplates are not particularly limited.

The liquid crystal layer 220 may be disposed on the line plate 211. Theliquid crystal layer 220 may include an alignment layer 221 on and underthe layer 220 to initially align the liquid crystal material includedtherein. Details (e.g., a liquid crystal material, an alignment layermaterial, a method of forming liquid crystal layer, a thickness ofliquid crystal layer, or the like) of the liquid crystal material andthe alignment layer are known and are not particularly limited.

A lower polarizer 300 is provided under the lower substrate. Materialsand structures of the polarizer 300 are known and are not particularlylimited. A backlight unit (e.g., emitting blue light) may be disposedunder the polarizer 300. An upper optical element or an upper polarizer300 may be provided between the liquid crystal layer 220 and thetransparent substrate 240, but is not limited thereto. For example, theupper polarizer 300 may be disposed between the liquid crystal layer 220and the photoluminescent layer 230. The polarizer may be any suitablepolarizer that used in a liquid crystal display device. The polarizermay be TAC (triacetyl cellulose) having a thickness of less than orequal to about 200 μm, but is not limited thereto. In an embodiment, theupper optical element may be a coating that controls a refractive indexwithout a polarization function.

The backlight unit includes a light source 110. The light source mayemit blue light or white light. The light source may include a blue LED,a white LED, a white OLED, or a combination thereof, but is not limitedthereto.

The backlight unit may further include a light guide panel 120. In anembodiment, the backlight unit may be an edge-type lighting. Forexample, the backlight unit may include a reflector, a light guide panelprovided on the reflector and providing a planar light source with theliquid crystal panel 200, at least one optical sheet on the light guidepanel, for example, a diffusion plate, a prism sheet, and the like, or acombination thereof, but is not limited thereto. The backlight unit maynot include a light guide panel. In an embodiment, the backlight unitmay be a direct lighting. For example, the backlight unit may have areflector, and may have a plurality of fluorescent lamps disposed on thereflector at regular intervals, or may have an LED operating substrateon which a plurality of light emitting diodes may be disposed, adiffusion plate thereon, and optionally at least one optical sheet.Details (e.g., each component of a light emitting diode, a fluorescentlamp, light guide panel, various optical sheets, and a reflector) ofsuch a backlight unit are not particularly limited.

A black matrix (BM) 241 is provided under the transparent substrate 240and has openings and hides a gate line, a data line, and a thin filmtransistor of the line plate on the lower substrate. For example, theblack matrix 241 may have a lattice shape. The photoluminescent layer230 is provided in the openings of the black matrix 241 and has aquantum dot-polymer composite pattern including a first section (R)configured to emit a first light (e.g., red light), a second section (G)configured to emit a second light (e.g., green light), and a thirdsection (B) configured to emit/transmit, for example blue light. Ifdesired, the photoluminescent layer may further include at least onefourth section. The fourth section may include quantum dots that emitlight of a different color (e.g., cyan, magenta, and yellow) from lightemitted from the first to third sections.

In the photoluminescent layer 230, sections forming a pattern may berepeated corresponding to pixel areas formed on the lower substrate. Atransparent common electrode 231 may be provided on the photoluminescentlayer.

The third section (B) configured to emit/transmit blue light may be atransparent color filter that does not change the emission spectrum ofthe light source. In this case, blue light emitted from the backlightunit may enter in a polarized state by passing through the polarizer andthe liquid crystal layer, and may be emitted as is. If desired, thethird section may include quantum dots emitting blue light.

If desired, the display device may further have a blue light blockinglayer (blue filter) or a first optical filter layer. The blue lightblocking layer may be disposed between lower surfaces of the firstsection (R) and the second section (G) and the upper substrate 240, oron the upper surface of the upper substrate 240. The blue light blockinglayer may be a sheet having an opening in a region corresponding to apixel area (a third section) displaying blue, and thus formed in aregion corresponding to the first and second sections. That is to say,the first optical filter layer may be disposed at the positions exceptthe position overlapped with the third section, and integrally therewithas shown in FIG. 4, but is not limited thereto. For example, at leasttwo first optical filter layers may be disposed leaving a space at eachposition overlapped with the first and second sections.

The first optical filter layer may block light having, for example, apredetermined wavelength region in the visible light region and maytransmit light in the other wavelength regions, and, for example, mayblock blue light and may transmit light except the blue light. Forexample, the first optical filter layer may transmit green light, redlight, and/or yellow which is a mixed color thereof.

The first optical filter layer may block, e.g., substantially block, forexample, blue light having a wavelength of less than or equal to about500 nm, and may have a property to transmit a wavelength region betweenthe remaining visible light wavelength region of greater than about 500nm and less than or equal to about 700 nm.

For example, the first optical filter layer may have a lighttransmittance of greater than or equal to about 70%, greater than orequal to about 80%, greater than or equal to about 90%, or about 100%for the other visible light in greater than or equal to 500 nm and lessthan or equal to about 700 nm.

The first optical filter layer may be a polymer thin film including adye and a pigment absorbing a wavelength which is to be blocked, and mayabsorb blue light having a wavelength of less than or equal to 480 nm asmuch as greater than or equal to about 80%, greater than or equal toabout 90%, greater than or equal to about 95%, but may have a lighttransmittance of greater than or equal to about 70%, greater than orequal to about 80%, greater than or equal to about 90%, and about 100%to the other visible light at greater than about 500 nm and less than orequal to about 700 nm.

The first optical filter layer may block, e.g., substantially block(e.g., absorb), blue light having a wavelength of less than or equal toabout 500 nm by absorbing the same, and may selectively transmit, forexample, green light, or red light. In this case, at least two firstoptical filter layers may be disposed spacing apart at each positionwhich is overlapped with each of the first to second sections. Forexample, the first optical filter layer selectively transmitting redlight may be disposed in a position which is overlapped with the redlight emitting section, and the first optical filter layer selectivelytransmitting green light may be disposed on a position which isoverlapped with the green light emitting section. For example, the firstoptical filter layer may include a first region to block (e.g., absorb)blue light and red light and to selectively transmit light in apredetermined range (e.g., greater than or equal to about 500 nm,greater than or equal to about 510 nm, or greater than or equal to orabout 515 nm and less than or equal to about 540 nm, less than or equalto about 535 nm, less than or equal to about 530 nm, less than or equalto about 525 nm, or less than or equal to about 520 nm), a second regionto block (e.g., absorb) blue light and green light and to selectivelytransmit light in a predetermined range (e.g., greater than or equal toabout 600 nm, greater than or equal to about 610 nm, or greater than orequal to about 615 nm and less than or equal to about 640 nm, less thanor equal to about 635 nm, less than or equal to about 630 nm, less thanor equal to about 625 nm, or less than or equal to about 620 nm), or acombination thereof. The first region may be disposed at a positionoverlapped with the green light emitting section and the second regionmay be disposed at a position overlapped with the red light emittingsection. The first region and the second region may optically beisolated. Such a first optical filter layer may contribute toimprovement of color purity of the display device.

The first optical filter layer may be a reflective filter including aplurality of layers (e.g., inorganic material layer) having differentrefractive indexes, and for example, may be formed by alternatelystacking two layers having different refractive indexes, for example, byalternately stacking a layer having a high refractive index and a layerhaving a low refractive index. As a refractive index difference betweenthe layer having the high refractive index and the layer having the lowrefractive index is higher, the provided first optical filter layer hasthe higher selectivity to a wavelength. A thickness and the stackingnumber of the layer having a high refractive index and the layer havinga low refractive index may be determined according to a refractive indexof each layer and a reflected wavelength, for example, each layer havinga high refractive index may have a thickness of about 3 nm to about 300nm, and each layer having a low refractive index may have a thickness ofabout 3 nm to about 300 nm.

The total thickness of the first optical filter layer may be, forexample, about 3 nm to about 10,000 nm, for example about 300 nm toabout 10,000 nm, for example about 1,000 nm to about 10,000 nm. Alllayers having a high refractive index may have the same thickness andthe same material or different from each other, and all layers having alow refractive index may have the same thickness and the same materialor different from each other.

The display device may further include a second optical filter layer(e.g., a red/green or yellow light recycle layer) disposed between thephotoluminescent layer and the liquid crystal layer (e.g., thephotoluminescent layer and the upper polarizer), transmitting at least aportion of third light, and reflecting at least a portion of the firstlight and/or second light. The second optical filter layer may reflectlight in a wavelength region of greater than about 500 nm. The firstlight may be red light, the second light may be green light, and thethird light may be blue light.

In the display device according to an embodiment, the second opticalfilter layer may be formed as an integrated layer having a relativelyplanar surface.

In an embodiment, the second optical filter layer may include amonolayer having a low refractive index, for example, the second opticalfilter may be a transparent thin film having a refractive index of lessthan or equal to about 1.4, less than or equal to about 1.3, or lessthan or equal to about 1.2.

The second optical filter layer having a low refractive index may be,for example, a porous silicon oxide, a porous organic material, a porousorganic/inorganic composite, or a combination thereof.

In an embodiment, the second optical filter layer may include aplurality of layers having different refractive indexes, for example,the second optical filter layer may be formed by alternately stackingtwo layers having different to refractive indexes, or for example, maybe formed by alternately stacking material having a high refractiveindex and material having a low refractive index.

The layer having a high refractive index in the second optical filterlayer may include, for example, a hafnium oxide, a tantalum oxide, atitanium oxide, a zirconium oxide, a magnesium oxide, a cesium oxide, alanthanum oxide, an indium oxide, a niobium oxide, an aluminum oxide,and a silicon nitride, or a combination thereof, but according toembodiments, the layer having a high refractive index may include avariety of materials having a higher refractive index than the layerhaving a low refractive index.

The layer having a low refractive index in the second optical filterlayer may include, for example, a silicon oxide, but according toembodiments, the layer having a low refractive index in the secondoptical filter layer may include a variety of materials having a lowerrefractive index than the layer having a high refractive index.

As the refractive index difference between the layer having a highrefractive index and the layer having a low refractive index is thehigher, the second optical filter layer may have the higher wavelengthselectivity.

In the second optical filter layer, each thickness of the layer having ahigh refractive index and the layer having a low refractive index andthe stacking number thereof may be determined depending upon arefractive index of each layer and the reflected wavelength, forexample, each layer having a high refractive index in the second opticalfilter layer may have a thickness of about 3 nm to about 300 nm, andeach layer having a low refractive index in the second optical filterlayer may have a thickness of about 3 nm to about 300 nm. The totalthickness of the second optical filter layer may be, for example, about3 nm to about 10,000 nm, for example about 300 nm to about 10,000 nm, orabout 1,000 nm to about 10,000 nm. Each of the layer having a highrefractive index and the layer having a low refractive index in thesecond optical filter layer may have the same thickness and materials ordifferent thickness and materials from each other.

The second optical filter layer may reflect at least a portion of thefirst light (R) and the second light (G) and may transmit at least aportion (e.g., whole portion) of the third light (B). For example, thesecond optical filter layer may transmit only the third light (B) in ablue light wavelength region having a wavelength region of less than orequal to about 500 nm and light in a wavelength region of greater thanabout 500 nm, which is green light (G), yellow light, red light (R), orthe like, may be not passed through the second optical filter layer 140and reflected. The reflected green light and red light may pass throughthe first and second sections and to be emitted to the outside of thedisplay device 10.

The second optical filter layer may reflect a wavelength region ofgreater than about 500 nm in greater than or equal to about 70%, greaterthan or equal to about 80%, or greater than or equal to about 90%, orabout 100%.

Meanwhile, the second optical filter layer may have a transmittance in awavelength region of less than or equal to about 500 nm of, for example,greater than or equal to about 90%, greater than or equal to about 92%,greater than or equal to about 94%, greater than or equal to about 96%,greater than or equal to about 98%, greater than or equal to about 99%,or about 100%.

The display device may exhibit improved luminance (e.g., greater than orequal to about 100 nits (candelas per square meter)) and a wide viewingangle (e.g., greater than or equal to about 160°).

An embodiment provides an electronic device including the quantumdot-polymer composite. The device may include a light emitting diode(LED), an organic light emitting diode (OLED), a sensor, a solar cell,an imaging sensor, or a liquid crystal display (LCD), but is not limitedthereto. The device has no particular limit regarding a structure and amaterial.

In an embodiment, an electronic device including the quantum dot-polymercomposite may include an electroluminescent diode. In theelectroluminescent device, the emission layer including theaforementioned quantum dot-polymer composite may be disposed between theanode and the cathode facing each other.

In an embodiment, an anode disposed on a transparent substrate mayinclude a metal oxide-based transparent electrode (e.g., ITO), and acathode may include a metal (Mg, Al, etc.) having a predetermined (e.g.,relatively low) work function. For example,poly((9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-s-butylphenyl)diphenylamine))(TFB), poly(N-vinylcarbazole) (PVK), or a combination thereof as a holetransport layer, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate(PEDOT:PSS), a p-type metal oxide, or a combination thereof as a holeinjection layer, or a combination thereof may be disposed between thetransparent electrode and the emission layer. An electron auxiliarylayer (e.g., electron transport layer, etc.) may be disposed between thequantum dot emission layer and the cathode (refer to: FIG. 7).

In an embodiment, the light emitting device may have an invertedstructure. Herein, a cathode disposed on a transparent substrate mayinclude a metal oxide-based transparent electrode (e.g., ITO, fluorinedoped tin oxide (FTO), etc.), and an anode may include a metal (e.g.,Au, Ag, etc.) of a predetermined (e.g., relatively high) work function.For example, an n-type metal oxide (ZnO) may be disposed between thecathode and the emission layer as an electron auxiliary layer (e.g., anelectron transport layer (ETL)). A hole auxiliary layer (e.g., a holetransport layer (HTL) including TFB, PVK, or a combination thereof, ahole injection layer including MoO₃ or other p-type metal oxide), or acombination thereof may be disposed between the metal anode and thequantum dot emission layer. (Refer to FIG. 8) Hereinafter, theembodiments are illustrated in more detail with reference to examples.However, they are exemplary examples of the present disclosure, and thepresent disclosure is not limited thereto.

EXAMPLES Analysis Methods 1. Ultraviolet-Visible (UV-Vis) Spectroscopy

A UV spectroscopy is performed by using an Agilent Cary 5000spectrometer to obtain a UV-Visible absorption spectrum.

2. Photoluminescence Analysis

A photoluminescence (PL) spectrum of a quantum dot-polymer composite atan irradiation wavelength of 458 nanometers (nm) (532 nm for a redquantum dot (QD)) is obtained by using a Hitachi F-7000 spectrometer.

3. Photo-Conversion Efficiency (CE)

A photo-conversion efficiency of a quantum dot-polymer composite film isobtained by inserting the quantum dot-polymer composite film between alight guide panel and an optical sheet of 60-inch television (TV)equipped with blue LED having a peak wavelength of 449 nm, operating theTV to analyze photoluminescence characteristics with a spectroradiometer(CS-2000, Konica Minolta Co.) positioned in front of and 45 centimeters(cm) away from the TV to obtain a photoluminescence spectrum of theemitted light, and calculating the photo-conversion efficiency (CE) fromthe photoluminescence spectrum.

4. Relative Quantum Efficiency (Quantum Yield: QY) of Quantum Dot

QY (quantum yield) of quantum dots in a quantum dot-polymer composite ismeasured in the following method:

QY=QY _(R) *OD _(R) /OD _(sample) *I _(sample) /I _(R)*(n _(sample))²/(n_(R))²

OD: Optical Density (determined by absorption intensity in a UVspectrum)

I: Integrated Intensity (a total integral value of a PL spectrum-phasedemission peak area)

n: a refractive index of a solvent

_(R): Reference dye (ex. Coumarine-green, rhodamine 6G—red)

Sample: synthesized QD sample

5. Luminance and Luminous Efficiency of Quantum Dot-Polymer Composite

(1) Luminance Measurement of Quantum Dot-Polymer Composite:

A quantum dot-polymer composite film is inserted between a light guidepanel and an optical sheet of 60 inch TV equipped with blue LED having apeak wavelength of 449 nm. Luminance of the quantum dot-polymercomposite is measured by operating TV and using a PSI DARSA-5200spectrometer in front of and about 45 cm away from the TV.

(2) Measurement of Photo-Conversion Efficiency (CE) of QuantumDot-Polymer Composite:

A quantum dot-polymer composite film is put in an integrating sphere,QE-2100 (Otsuka Ellectronics Co., LTD) and photo-conversion efficiency(CE %) of the composite film is measured, while the quantum dot-polymercomposite film is radiated by excitation light of 450 nm. Thephoto-conversion efficiency of the film is obtained in theaforementioned method.

6. TEM (Transmission Electron Microscopy) Analysis

A transmission electron microscope analysis is performed by using aTitan ChemiSTEM electron microscope.

Synthesis Example: Preparation of Scattering Body-Dispersion (1) ControlSynthesis Example, Comparative Synthesis Example 1-1, and SynthesisExample 1-1: Preparation of Scattering Body-Dispersion

TiO₂ particulates (average particle diameter of 200 nm) (ControlSynthesis Example), core-shell TiO₂ particulates (including an SiO₂ core(average particle diameter of 400 nm) and a TiO₂ shell (shell thicknessof 35 nm)) (Comparative Synthesis Example 1-1), and hollow silica SiO₂particulates (average particle diameter of 300 nm, hollow diameter of250 nm) (Synthesis Example 1-1) in each amount of 20 weight percent (wt%) are respectively added to propylene glycol monomethyl ether acetate(PGMEA) as a solvent based on a total weight of each dispersion as ascattering body, that is, a weight sum of the solvent and the scatteringbody, and the mixture is ball-milled for 60 minutes to prepare eachscattering body-dispersion according to the Control Synthesis Example,Comparative Synthesis Example 1-1, and Synthesis Example 1-1.

The scattering body-dispersions are respectively coated in an equalamount to have the same thickness and dried, and a TEM image of across-section thereof is shown in FIG. 9. As shown in a left image ofFIG. 9, when a scattering body is included in the same amount (the samewt %), a film including hollow silica according to Synthesis Example 1-1has smaller hollow silica density and thus includes much more scatteringbody particles in the same area than a film according to the ControlSynthesis Example or Comparative Synthesis Example 1-1. Without beingbound to any specific theory, it is believed that a scattering degreemay increase with an increase of the number of scattering bodies, and asshown in the following experiment result, scattering efficiency mayincrease, e.g., significantly, as the number of scattering bodiesincreases. A right image of FIG. 9 is obtained by enlarging the leftimage. A non-hollow particulate-shaped scattering body of the ControlSynthesis Example, a core shell-shaped scattering body of ComparativeSynthesis Example 1-1, and a hollow particulate shaped scattering bodyof Synthesis Example 1-1 are clearly different one another.

(2) Comparative Synthesis Example 1-2 and Synthesis Example 1-2:Synthesis of Scattering Body-Dispersion

Each scattering body-dispersion is prepared according to the same methodas Comparative Synthesis Example 1-1 and Synthesis Example 1-1 byfurther adding a dispersing agent binder facilitating dispersion of ascattering body in addition to PGMEA as a solvent.

Specifically, each scattering body-dispersion according to ComparativeSynthesis Example 1-2 and Synthesis Example 1-2 is prepared by adding apolyester having a weight average molecular weight of about 3,000 g/molas a dispersing agent to propylene glycol monomethyl ether acetate(PGMEA) as a solvent to be 20 wt %, based on a total weight ofdispersion, respectively adding a core-shell TiO₂ particulate as inComparative Synthesis Example 1-1 and hollow silica as in SynthesisExample 1-1 to the solvent to be 20 wt %, based on a total weight of thesolvent, the dispersing agent, and the scattering body and then,ball-milling each mixture for 60 minutes.

Example: Preparation of Composition for Manufacturing QuantumDot-Polymer Composite

Chloroform dispersion of quantum dots (InP/ZnS core-shell quantum dotshaving oleic acid as an organic ligand on the surface, emitting redlight) is prepared. The quantum dot chloroform dispersion is mixed witha solution of a quaternary copolymer binder of methacrylic acid, benzylmethacrylate, hydroxyethyl methacrylate, and styrene (acid value: 130 mgKOH/g, molecular weight: 8,000 g/mol, mole ratio of methacrylicacid:benzyl methacrylate:hydroxyethyl methacrylate:styrene is61.5%:12%:16.3%:10.2%) (solid content of 30 wt % in propylene glycolmonomethyl ether acetate) to prepare quantum dot-binder dispersion. Thequantum dots are uniformly dispersed in the quantum dot-binderdispersion, when examined with naked eyes.

Each composition for manufacturing a quantum dot-polymer compositeaccording to the Control Example, Comparative Examples 1-1 and 1-2, andExamples 1-1 and 1-2 is prepared by mixing the quantum dot-binderdispersion with glycol-di-3-mercaptopropionate represented by ChemicalFormula 2 (hereinafter, 2T), hexaacrylate represented by ChemicalFormula 3 as a photopolymerizable monomer, an oxime ester compound as aninitiator, and the scattering body-dispersion according to SynthesisExample:

Each composition includes 25 wt % of a solid, and based on a totalamount of the solid, 43 wt % of quantum dots, 12.0 wt % of thequaternary copolymer binder as a dispersing agent for dispersing thequantum dots, 10.0 wt % of hexaacrylate represented by Chemical Formula3 as a photopolymerizable monomer, 0.5 wt % of an oxime ester compoundChemical Formula 3 as an initiator, 25 wt % of the thiol compound 2Trepresented by Chemical Formula 2, and 9.5 wt % of each scattering bodyof TiO₂ particulates (Control Synthesis Example), core-shell TiO₂(Comparative Synthesis Example), or hollow SiO₂ (Synthesis Example)respectively.

Preparation Example and Evaluation: Formation and Evaluation of QuantumDot-Polymer Composite Pattern

The compositions according to the Control Example, the Example, and theComparative Example are respectively spin-coated on a glass substrate at180 revolutions per minute (rpm) for 5 seconds to obtain each film. Thefilm is pre-baked at 100° C. Herein, each film according to the ControlExample, the Example, and the Comparative Example is prepared into twofilms having a different thickness, which are applied to the followingexperiment, and the results are shown.

A photoluminescence (PL) spectrum of the pre-baked film (PRB) isobtained by using a Hitachi F-7000 spectrometer as described in theaforementioned analysis method, and an emission peak, a full width athalf maximum (FWHM), and QE of the film are measured therefrom. Inaddition, a UV absorption rate (Abs) is obtained through UV-Visspectroscopy, and a photo-conversion efficiency (CE) is calculated fromthe photoluminescence spectrum, and the results are shown in Table 1.

Subsequently, the pre-baked film is radiated by light (wavelength: 365nm, intensity: 100 millijoules (mJ)) for one second under a mask havinga predetermined pattern, and then, developed with a potassium hydroxideaqueous solution (concentration: 0.043%, pH: 11) for 50 seconds toobtain a pattern (line width: 100 micrometers (μm)). When the pattern isradiated by blue light (wavelength of 450 nm), the pattern emits redlight. In addition, after once heating the pattern at 180° C. for 30minutes, an emission peak, a full width at half maximum (FWHM), QE, Abs,and a photo-conversion efficiency of the pattern are measured as in thepre-baked film, and the results are shown in Table 1.

TABLE 1 Control Comparative Comparative Example Example 1-1 Example 1-2Control Comparative Comparative Synthesis Synthesis Synthesis Scatteringbody- Example Example 1-1 Example 1-2 dispersion Experiment 1 Experiment2 Experiment 1 Experiment 2 Experiment 1 Experiment 2 Thickness (μm)6.30 6.60 6.30 6.70 6.70 6.80 PRB (Air Peak 543.5 543.8 548.7 546.3548.7 546.1 ref.) (nm) FWHM 36 36 38 38 38 38 (nm) QE 27.5% 27.9% 11.1%12.3% 11.4% 11.7% Abs 86.7% 87.5% 38.6% 40.4% 38.8% 39.9% CE 31.7% 31.9%28.8% 30.4% 29.4% 29.3% POB (Air Peak 544.5 545 547.9 547.2 547.3 547.7ref.) (nm) FWHM 36 36 38 38 38 39 (nm) QE 26.8% 27.4% 12.6% 13.7% 12.2%12.5% Abs 86.5% 87.2% 40.8% 42.3% 40.6% 42.3% CE 31.0% 31.4% 30.9% 32.4%30.0% 29.6% POB QE/   97%   98%  114%  111%  107%  107% PRB QE × 100%Example 1-1 Example 1-2 Synthesis Synthesis Scattering body- Example 1-1Example 1-2 dispersion Experiment 1 Experiment 2 Experiment 1 Experiment2 Thickness (μm) 6.60 6.66 7.00 7.20 PRB (Air Peak 544.4 543.7 543.4545.1 ref.) (nm) FWHM 36 36 36 36 (nm) QE 26.2% 26.6% 26.9% 27.1% Abs71.3% 71.9% 72.5% 73.1% CE 36.7% 37.0% 37.1% 37.1% POB (Air Peak 544.2544.3 544.9 544.9 ref.) (nm) FWHM 36 37 36 36 (nm) QE 26.3% 26.6% 27.3%27.6% Abs 75.2% 75.7% 76.5% 76.8% CE 35.0% 35.1% 35.7% 35.9% POB QE/ 100%  100%  101%  102% PRB QE × 100%

In Table 1, POB denotes a post-baked film, that is, a film obtained byheating the pre-baked film at 180° C. for 30 minutes after patterningit.

Referring to Table 1, each quantum dot-polymer composite film (orpattern) including hollow silica as a scattering body of Examples 1-1and 1-2 exhibits a relatively high photo-conversion efficiency (CE)compared with each film of the Control Example or Comparative Examples1-1 and 1-2. The post-baked pattern of the Control Example exhibits a CEof about 31%, but the patterns including hollow silica of Examples 1-1and 1-2 exhibit a CE of greater than or equal to 35%. On the other hand,the core-shell type quantum dot-polymer composite patterns ofComparative Examples 1-1 and 1-2 exhibit a similar photo-conversionefficiency (CE), but a lower absorption rate (Abs) than the core-shelltype quantum dot-polymer composite pattern of the Control Example.

On the other hand, FIG. 10 shows reflectance (SCI) results of eachquantum dot-polymer composite of Experiment 2 of the Control Example andExperiment 2 of Example 1-2. Referring to FIG. 10, the composite filmincluding hollow silica as a scattering body of Example 1-2 exhibitslower reflectance than the composite film including TiO₂ particulates asscattering bodies of the Control Example. Accordingly, a composition formanufacturing a quantum dot-polymer composite, which includes hollowsilica as a scattering body according to an embodiment has an effect ofreducing reflectance.

Additional Experiment: Characteristics Evaluation of Composite-ShapedScattering Body

A composition for manufacturing a quantum dot-polymer composite isprepared according to the same method as the Examples except for using amixed scattering body-dispersion including TiO₂ particulates of theControl Synthesis Example and hollow silica of Synthesis Example 1-1 ina predetermined amount, that is, a weight of hollow silica relative to atotal weight of scattering bodies (e.g., total weight of solids in thescattering body-dispersion) in a range of 3 wt % to 100 wt % in the sametotal weight of solids as that of each scattering body-dispersionaccording to the Examples.

The composition is respectively spin-coated on a glass substrate at 180rpm for 5 seconds to obtain a film, and the film is pre-baked at 100° C.and once additionally post-baked at 180° C. for 30 minutes. CE, quantumefficiency (QE), and a maintenance percent of each obtained film areshown in FIGS. 11 to 13.

Referring to FIGS. 11 to 13, when a content of hollow silica is about 20wt %, based on a total content of the scattering body, the mostexcellent characteristics of CE, quantum efficiency (QE), and amaintenance percent are obtained.

While this disclosure has been described in connection with what ispresently considered to be practical example embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A composition comprising a quantum dot, adispersing agent for dispersing the quantum dot, a polymerizable monomercomprising a carbon-carbon double bond, an initiator, a hollow metaloxide particulate, and a solvent.
 2. The composition of claim 1, whereinthe hollow metal oxide particulate comprises a titanium oxide, a siliconoxide, a barium oxide, a zinc oxide, a zirconium oxide, or a combinationthereof.
 3. The composition of claim 1, wherein the hollow metal oxideparticulate comprises TiO₂, SiO₂, BaTiO₃, Ba₂TiO₄, ZnO, ZrO₂, or acombination thereof.
 4. The composition of claim 1, wherein an averageparticle size of the hollow metal oxide particulate ranges from about200 nanometers to about 500 nanometers.
 5. The composition of claim 1,wherein an average particle size of the hollow metal oxide particulateranges from about 250 nanometers to about 450 nanometers.
 6. Thecomposition of claim 1, wherein an average size of a hollow portion inthe hollow metal oxide particulate is greater than or equal to about 10nanometers and less than about 500 nanometers.
 7. The composition ofclaim 1, wherein an average size of a hollow portion in the hollow metaloxide particulate is greater than or equal to about 30 nanometers andless than or equal to about 450 nanometers.
 8. The composition of claim1, wherein the quantum dot comprises a Group II-VI compound, a GroupIII-V compound, a Group IV-VI compound, a Group IV element or compound,a Group I-III-VI compound, a Group I-II-IV-VI compound, or a combinationthereof.
 9. The composition of claim 1, wherein the dispersing agentcomprises a carboxyl group-containing polymer and the carboxylgroup-containing polymer comprises a copolymer of a monomer combinationcomprising a first monomer comprising a carboxyl group and acarbon-carbon double bond, a second monomer comprising a carbon-carbondouble bond and a hydrophobic moiety and not comprising a carboxylgroup, and optionally a third monomer comprising a carbon-carbon doublebond and a hydrophilic moiety and not comprising a carboxyl group; amultiple aromatic ring-containing polymer comprising a backbonestructure in which two aromatic rings are bound to a quaternary carbonatom that is a constituent atom of another cyclic moiety in the backboneand comprising a carboxyl group; or a combination thereof.
 10. Thecomposition of claim 9, wherein the carboxyl group-containing polymerhas an acid value of greater than or equal to about 50 milligrams ofpotassium hydroxide per gram less than or equal to about 240 milligramsof potassium hydroxide per gram.
 11. The composition of claim 1, furthercomprising a thiol compound comprising a thiol group at a terminal endof the thiol compound.
 12. The composition of claim 11, wherein thethiol compound is represented by Chemical Formula 1:

wherein, in Chemical Formula 1, R¹ is hydrogen; a substituted orunsubstituted C1 to C30 linear or branched alkyl group; a substituted orunsubstituted C6 to C30 aryl group; a substituted or unsubstituted C3 toC30 heteroaryl group; a substituted or unsubstituted C3 to C30cycloalkyl group; a substituted or unsubstituted C3 to C30heterocycloalkyl group; a C1 to C10 alkoxy group; a hydroxy group; —NH₂;a substituted or unsubstituted C1 to C30 amine group of the formula—NRR′, wherein R and R′ are independently hydrogen or a C1 to C30 linearor branched alkyl group and are not simultaneously hydrogen; anisocyanate group of the formula —R-M=C═O, wherein R is a substituted orunsubstituted C1 to C20 alkylene group and M is an organic or inorganiccation; a halogen; —ROR′ wherein R is a substituted or unsubstituted C1to C20 alkylene group and R′ is hydrogen or a C1 to C20 linear orbranched alkyl group; an acyl halide of the formula —RC(═O)X, wherein Ris a substituted or unsubstituted alkylene group and X is a halogen;—C(═O)OR′, wherein R′ is hydrogen or a C1 to C20 linear or branchedalkyl group; —CN; —C(═O)ORR′ or —C(═O)ONRR′, wherein R and R′ areindependently hydrogen or a C1 to C20 linear or branched alkyl group, L₁is a carbon atom, a substituted or unsubstituted C1 to C30 alkylenegroup, a substituted or unsubstituted C1 to C30 alkylene group whereinat least one methylene moiety is replaced by a sulfonyl moiety, acarbonyl moiety, —O—, —S—, —SO—, —C(═O)O—, —C(═O)NR— wherein, R ishydrogen or a C1 to C10 alkyl group, or a combination thereof, asubstituted or unsubstituted C3 to C30 cycloalkylene group, asubstituted or unsubstituted C6 to C30 arylene group, a substituted orunsubstituted C3 to C30 heteroarylene group, or a substituted orunsubstituted C3 to C30 heterocycloalkylene moiety, Y₁ is a single bond;a substituted or unsubstituted C1 to C30 alkylene group; a substitutedor unsubstituted C2 to C30 alkenylene group; a C1 to C30 alkylene groupor a C2 to C30 alkenylene group wherein at least one methylene moiety isreplaced by a sulfonyl moiety, a carbonyl moiety, —O—, —S—, —S(═O)—,—C(═O)O—, —C(═O)NR—, wherein R is hydrogen or a C1 to C10 linear orbranched alkyl group, —NR—, wherein R is hydrogen or a C1 to C10 linearor branched alkyl group, or a combination thereof, m is an integer of 1or more, k1 is 0 or an integer of 1 or more, k2 is an integer of 1 ormore, and the sum of m and k2 is an integer of 3 or more, provided thatm does not exceed the valence of Y₁ and the sum of k1 and k2 does notexceed the valence of L₁.
 13. The composition of claim 1, wherein anamount of the quantum dot is greater than or equal to about 10 weightpercent, and an amount of the hollow metal oxide particulate is greaterthan or equal to about 5 weight percent, based on a total weight ofsolids in the composition.
 14. The composition of claim 1, wherein anamount of the hollow metal oxide particulate is about 5 weight percentto about 80 weight percent, based on a total weight of solids in thecomposition.
 15. A quantum dot-polymer composite comprising thecomposition of claim
 1. 16. A display device, comprising a light source,and a photoluminescent element, wherein the photoluminescent elementcomprises the quantum dot-polymer composite of claim 15, and the lightsource is configured to provide the photoluminescent element withincident light.
 17. The display device of claim 16, wherein the incidentlight has a photoluminescence peak wavelength of about 440 nanometers toabout 460 nanometers.
 18. The display device of claim 16, wherein thephotoluminescent element comprises a sheet comprising the quantumdot-polymer composite.
 19. The display device of claim 16, wherein thephotoluminescent element has a stack structure comprising a substrateand a photoluminescent layer disposed on the substrate, wherein thephotoluminescent layer comprises a pattern of the quantum dot-polymercomposite, and the pattern comprises at least one repeating sectionemitting light in a predetermined wavelength.
 20. The display device ofclaim 19, wherein the pattern comprises a first section configured toemit a first light and a second section configured to emit a secondlight having a different center wavelength from the first light.